Zack Underwood
Zack Danger Underwood trans 01
Gender: Male
Age: 14
Friends and Family
Eileen Underwood (mother)
Marcus Underwood (father)
Two unnamed brothers
Milo Murphy
Melissa Chase
Love interests:
Jackie (One Time)
Behind the Scenes
First Appearance:
  "Going the Extra Milo"
Last Appearance:
  A Christmas Peril
Voiced by:
Mekai Curtis (speaking voice)
Aaron Daniel Jacob (singing voice)

Zack Underwood is one of the main characters in Milo Murphy's Law, voiced by Mekai Curtis. He is the best friend of Milo Murphy and Melissa Chase.


Zack is the new kid in town and the voice of reason when things get out of hand. While the rest of the town is used to Milo, Zack is trying to enjoy the adventure of being Milo's best friend without getting destroyed. He wants to follow Milo because he wants a change from common life. In fact, he accepts going to school with Milo because his adventures are unique. (Going the Extra Milo)

He also wants to be safe enough though. In the episode Sunny Side Up, he has no problems on doing a science project with Milo, even knowing that it's extremely hard, but when they made it he didn't let Milo get near to make the project safe.

Maybe because he's new, he seems to not be fully aware of what Murphy's law can cause. He often says that things couldn't go worse, or he thinks that is some case, nothing wrong can happen. Zack is also fairly self-conscious about previously being part of The Lumberzacks, at times trying to conceal the fact from his friends while at others actually hoping to be recognized for the role.

Physical Appearance

Zack has brown skin and black hair. He wears a short-sleeved yellow shirt with a white long-sleeved shirt underneath, gray pants, and blue and white sneakers.


Early life

Prior to moving to Danville - or at least the area of it where he currently resides - Zack was the leader of the boy band The Lumberzacks, who gained some popularity from their song Chop Away at My Heart. Zack later left the band and came to be embarrassed by the fact of his membership in it, as described in Secrets and Pies. In Murphy's Lard it is revealed that, due to an incident on a boat ride with his parents, Zack has developed a crippling phobia of fish.

Meeting Milo

Zack first meets Milo in Going the Extra Milo when he is on his way to attend his first day of school, with the pair meeting at the bus stop. After seeing several other students - including Bradley Nicholson, Chad, and Melissa Chase - purposefully keep their distance from Milo, Zack questions the reasoning behind it and initially wonders if Milo is supposed to be a "tough guy." He soon learns that Milo is, in fact, the subject of ongoing mishaps due to Murphy's law, which Zack begins to experience as the two are forced to flee from a section of concrete pipe that has fallen off of a truck. The two are able to escape due to Milo's quick-thinking but are forced to chase the bus.

Zack and Milo endure several other calamities - an oil spill that catches fire, a pack of wolves, and a beehive that becomes stuck on the head of one of those wolves - as they continue their pursuit of their school bus. After they end up in the city sewers, Zack announces his intentions to go his own way, only to gain a new perspective on the unusual situation from Milo, who notes how much more exciting their morning has been than that of their classmates. The two are then caught in a flood caused by the absence of the pipe they escaped from previously, washed into a river, and then thrown off a cliff only to land on top of a flying saucer. However, as they are about to be apparently dissected by the aliens, Zack informs the extraterrestrials that they may become late for school, and the aliens then teleport the pair to their first-period classroom just in time. The pair is elated but then realize that their lunches have been destroyed, only to discover that Melissa has taken care of the situation due to starting a betting pool in which the different students on the bus bet food on whether or not Zack and Milo would make it to school on time.

Further adventures

In Sunny Side Up Zack teams up with Milo and Melissa for a science project involving creating a device that will enable an egg to survive a long fall intact. They are eventually successful, though only after destroying an inordinate number of eggs, and Zack and Melissa take their last remaining egg and the device home with them. Zack then has a nightmare about the device being destroyed, but wakes up to find that it wasn't real; unfortunately, the egg is smashed before they can take part in the experiment. Fortunately, an egg Milo had put in his pocket earlier turns out to be intact, allowing them to test their device in front of the class. The device and the egg end up going through an insane amount of punishment after being hit by a delivery truck, but ultimately the egg lands safely-only to be eaten by Diogee after Zack's group is graded with an A.

In Rooting for the Enemy Zack has joined the Jefferson County Middle School Geckos football team and pleads with Milo and Melissa to attend his first game, which Milo gets permission to do since Coach Nolan Mitchell is convinced that the team will lose.

In The Undergrounders, Zack and his friends become separated from their class while on a subway to the museum and end up coming across a subterranean group known as the undergrounders.

In The Doctor Zone Files, Zack and Melissa are invited to a The Doctor Zone Files marathon by Milo and his sister Sara Murphy in anticipation of going to see the new Doctor Zone Files movie. Milo and Melissa, while questioning whether Time Ape is an ape with a clock for a head or a clock with the body of an ape, get into a dispute with some hardcore Doctor Zone fans. When the two hit upon the idea that Time Ape is actually Doctor Zone's brother, the fans are disgusted, but Zack and Melissa are later proven right.

In The Note, Zack and his friends attempt to recover the signature page from a bulk doctor's note for Milo, as otherwise he will have several unexcused absences and have to repeat seventh grade. After chasing the note through an office building, a parade and a recycling center, they get it but are stopped by Elliot, much to their annoyance. But he is soon be integrated, much to their shock and confusion.

In Party of Peril Zack and Melissa convince Milo's parents to throw him an actual birthday party as opposed to the limited affair he's had previously.

In Smooth Opera-tor he attends an opera for extra credit for Ms. White's class.

In Worked Day he and his class visit their parents for career day. They watch Milo's father at the water center- where a flood occurs, Melissa's father at the Fish Hatchery, where Milo starts a fire with water, and his mother at the Hospital, where an MRI machine becomes a super magnet.

In The Wilder West he, Milo, Melissa and a Sara go to the Nowhere Desert Dude Ranch, while Sara wonders off to see if an episode of Doctor Zone was filmed there. While riding horses they are chased down by a girl named Jackie, who he develops a crush on. The three spend the day with her and it takes him surviving an avalanche, raging bull and flash flood to over Jackie. The two them did their goodbyes. He and Milo help Sara in the car when they realize she is not with them.

In Family Vacation he and Melissa watch Diogee while the Murphies go on a road trip. They also relax in a pool.

In Murphy's Lard he, Milo and Melissa go to Lard World and learn that Melissa has a fear of roller coasters. They take her to the amusement park's largest roller coaster, greased thunder, where he immediately gets off when Melissa points out that they would be on a roller coaster with Milo and leaves the two to deal with Murphy's Law on a roller coaster. As they are about to lead he is hit with a goldfish in a plastic bag and freaks out.

In Secrets and Pies, he tries to keep his past involvement as a singer (and title character) in a boy band from being discovered by Milo and Melissa. He ultimately fails when Veronica reveals it and they watch the music video for Chop Away at my Heart online.

In Athledecamathalon he, Milo, Melissa, Mort, and Chad participate in a combined scholastic and athletic event, which they just heard of, against the Middletown Middle School Middlemen, who knew about it for three months. Things go poorly until Murphy's Law makes it fair game for them. He somehow winds up stuck in a volleyball net in a tree with a hotdog cart defending a hotdog from seagulls. His team wins.

In The Substitute, he describes their substitute science teacher, Ms. Baxter, as burnt out. He assists Milo with chemicals until a drop spills and the entire class, save for Milo and Melissa, panics. After Milo creates a Sentient Blob he, Milo and Melissa freeze the blob with fire extinguishers.

In Time Out he and Milo go fishing with their fathers on the Murphy's boat. He is nervous about Murphy's Law but helps to get back to shore when the motor drives away.

In We're Going to the Zoo he and the Murphy siblings chase down Bridgette's t-shirts that were accidentally donated, only to discover that she intended to donate them.

In School Dance, he attends the school dance with Melissa and Milo. Chad was able to convince him and Melissa that two men were vampire hunters out to kill Mr. Drako. The three confront them and the pair leave. After the band vanishes, Milo asks him, Melissa, and Mort to fill in.

In Battle of the Bands he, Milo, Melissa, and Mort form a band. At first, he just wants to use the contest as practice to get the other members used to perform in front of others. However he runs into his old band, now called The Lumbermaxes, and Max taunts him into wanting to win; which affects his behavior with his new band. As Lumbermax is performing he gets nervous and volunteers to play all the instruments himself until he realizes what he is doing. The band performs A Bumpy Ride Tonight and does well. Max even offering him to rejoin, but he turns a deaf ear to the former leader's rejection.

In The Math Book, he goes with Melissa and Milo to school to get Melissa's math book. They get a key from Principal Milder but end up locking it in the classroom. They eventually get back in the room and get the key.

In The Llama Incident, he and his friends are dangling over a cliff on a branch. During this time his friends tell him about the infamous Llama Incident. He is impressed and uses that story to form an idea to get to safety which he calls The Woodpecker Incident.

In Missing Milo he and his friends narrowly escape a wave of lava. After Milo vanishes, he and Melissa go looking for him. Diogee finds Milo's backpack and they are chased by Brick and Savannah, but they avid the time travelers with help from Scott. They go to Milo's house and see him in the pilot episode of Doctor Zone, filmed in 1965. He goes with Melissa, Sara, and Diogee to Melissa's house, where she has a room dedicated to Murphy's Law and keep seeing two figures in most of the backgrounds. The group heads to the home of Orton Mahlson, the creator of Doctor Zone, to see if he knows anything. He gives them a letter from Milo telling them to meet him at Jefferson County Middle School at 3:00 PM. they arrive and are greeted by King Pistachion and his forces. Milo, along with Dakota and Cavendish, arrive shortly after and the six put up a fight on until all of them, except Milo and Diogee, are taken captive. Luckily, Diogee pees on the king's current day self and his forces vanish.

In Star Struck, he goes with Milo and Melissa to get Tobias Trollhammer's autograph. After the actor freaks out thinking Milo is a Menninkäinen and runs away he helps his friends chase him down.

In Disaster of My Dreams, he goes about his regular school day while Elliot follows Milo around all day.

In A Clockwork Origin, he goes with his friends to V-Tech to show Victor Verliezer his app, which is supposed to add an armadillo to any picture but instead makes a high pitched sound. After finding out that Veriliezer's new invention, C.I.D.D., is not his they search for his real creator at a lumberjack festival. Zack is hesitant about going in because of the Lumberzacks, but no one recognizes him, with the exception of a security guard. They find C.I.D.D.'s creator, Clyde Rickenbacker, and the five of them run away from V-tech. After they reveal that Verilezer mocks his customers, they abandon his products and he his company goes belly up. Zack's armadillo app finally works.

In Perchance to Sleepwalk, he goes camping with Milo and Melissa while his parents stay in a nearby resort. After Milo sleepwalks he and Melissa chase him while dealing with Murphy's Law. They catch up with him and bring Milo back to camp.

In Some Like it Yacht, he goes on the school yacht and gets stranded on an island. He, Mr. Drako, and the rest of the student on board, with the exception of Bradley, patch up the boat and scout out the island for resources while the majority of the faculty went feral almost instantly.

In Backward to School Night, he and his mom go to back-to-school-night along with Milo, Melissa and their dads. After their parents and Ms. Murawski are turned into toddlers, the children chase them around the school until Cavendish fixes the device that could turn them into adults again. He and his friends fall asleep from exhaustion while their parents watch them sleep.

In World Without Milo Zack protests Elliot's rudeness to Milo; in the alternate timeline in which Milo no longer exists, he and Melissa have not met until they both encounter Elliot, who is the only one to remember Milo's existence.

In The Race, he and Melissa help Milo deal with Murphy's law during a race and build him a makeshift finish line.

In Love Toboggan he and Melissa go skiing with Milo and his father. During the day they are nearly crushed by a giant snowman, chased down the mountainside by an avalanche, and flung from the ski resort to town on a toboggan. They crash into Sara and Neal before the toboggan becomes jet propulsion on a boiler. After Diogee disconnects the boiler from the sleigh, the three leave the older teenagers alone.

In The Island of Lost Dakotas he, Melissa and Milo are going to see Hamosaur with Zack impatiently waiting for Milo to find his shoes. He gives Milo a pair that has laces, which Milo reluctantly takes. On the way there he and Melissa are entangled in Milo's shoelaces and stuck to Hamosaur's tail. With Milo's quick thinking they are saved.

In Fungus Among Us he, Milo and Melissa are falling out of the sky when their hot air balloon popped, but are saved, inadvertently, by Cavendish and Dakota who then take Milo with them to 1965 with the two betting that it would not end well. During that time they are taken prisoner by the Pistachions and replaced by Pistachions in human costumes. They are locked in a cage at Lard World with Milo's family.

In Milo Murphy's Halloween Scream-a-Torium! he is the only one among his friends and Sara not dressed for the holiday. He says he grew out of it and checks out the decommissioned truck Milo had turned into a haunted house. He gets separated from the girls and realized the truck, which has no breaks or steering, has moved and is now dangling over a cliff. He and Milo pull the truck off the cliff before it rolls downhill dragging Elliot with them. They make their way through various warehouses before plummeting off another cliff. Parachutes then break their fall and they land in the courtyard of Jefferson County Middle School. He has regained his love of Halloween once again. While Milo, Sara and Melissa runaway in terror at the sight of an exhausted Elliot, he only does so when his father shows up dressed as a fish; his worst fear.

In A Christmas Peril, he and Melissa help Milo and Sara pick up the extended Murphy family during Christmas Eve while a blizzard is forming. The group is stranded when their car is buried under snow. They then take a horse-drawn carriage until it winds up stuck in a tree. They make their way to the mall, where they run into Milo and Sara's parents and have dinner at the Chinese restaurant. His parents join him along with Melissa's father, Mort, and Amanda.



Eileen Underwood

He was happy to visit his mom on career day and seemed satisfied when the other students noted how cool her job was. Eileen went with him when the school had a parent-teacher night, and the two of them exchanged friendly banter before the meeting ("Worked Day", " Backward to School Night").

Marcus Underwood

Zack expressed nervousness to his father when they went on a fishing trip with Milo and Martin. While Marcus did not initially believe his son over the existence of Murphy's Law, the two of them ended up working together to get the boat to shore ("Time Out").


Milo Murphy

Main Article: Zack and Milo's Relationship

Since Zack met Milo, they became friends. Sometimes Zack teases Milo copying his usual position. (As seen in the last seconds of Smooth Opera-tor.)

Melissa Chase

Main Article: Zack and Melissa's Relationship

He became good friends with Melissa through their mutual friendship with Milo. He gets along with her well since the two of them are more level-headed when it comes to Murphy's Law. They often cooperate with each other to finish a goal, as seen when they both work hard to protect their project from potential disasters in Sunny side Up. Melissa tells Zack to loosen up while Zack tends to worry about Melissa's absent-mindedness.

The Lumberzacks

Before Zack moved to Danville, he and his friends formed a lumberjack-themed boy band. The five enjoyed their fame together until he ended up moving away. When he saw them again, the band's new leader, Max, provoked a rivalry between the now-renamed Lumbermaxes and Zack's new band, Just Getting Started. After the performance, they tried in vain to get Zack to rejoin (Battle of the Bands).


Mort Schaeffer

Zack is on friendly terms with Mort. They are both players in the Jefferson County Middle School football team, and the two of them are a part of the band [[Just Getting Started]].

Amanda Lopez

Zack is on friendly terms with Amanda and has teased Milo over his interest in her.


Zack gets along well with Chad and was quick to go along with his 'vampire-hunter' theory, going out of his way to help him defend Mr. Drako (School Dance).


Sara Murphy

Zack is on good terms with Milo's sister and enjoys hanging out with her. They've ended up on a number of adventures together. 

Cavendish and Dakota

Although he doesn't know them very well, Zack is on friendly terms with Cavendish and Dakota.


Zack had a brief crush on the danger-seeking girl. He was attracted to her for less than a day (The Wilder West).


Screenshot (2974)
The image gallery for Zack Underwood may be viewed here.


  • In The Undergrounders, he appears to be claustrophobic, which is a fear of closed places; however, he says he's just 'claustro-avoidant'.
  • So far, Zack didn't appear once in The Little Engine That Couldn't.
  • He states he has a fear of fish.
    • Though he has a least attempted to conquer his fear of fish that aren't in a body of water, he goes fishing in Time Out.
  • His football jersey number is 19.
  • Like Ferb, Zack has separate voice actors for speaking and singing.
  • Zack being the voice of reason yet a best friend to the main character who is positive is similar to Gerald Johanssen from Hey Arnold! Dan Povenmire worked on Hey Arnold! before working on Milo Murphy's Law.
  • In Fungus Among Us, he mentioned that he has at least two younger brothers.
  • In Love Toboggan, it was shown he knows how to snow board.