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 dark eyes, brown skin, and thick, bushy black hair.

He wears a deep-yellow short-sleeved shirt over a white long-sleeved shirt, revealing only the collar and the sleeves of the latter, alongside a pair of light colored blue jeans with pockets and gray cuffs. His sneakers are a darker blue and white with white laces.

He is slightly taller than both Milo and Melissa and tends to stand with a bit of a slouch, giving off a 'chill' appearance. Likewise, he often sports a cocky, relaxed expression to the same effect.


Click here to view the history of Zack Underwood.



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").

His father loves to scare him constantly- and would do so every Halloween, coming up with creative new ways to scare him every year. Zack absolutely loved this and claims it was awesome. His father manages to do it again this year despite Zack's belief that Halloween no longer scares him ("Milo Murphy's Halloween Scream-a-Torium!").


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, as 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 often seems amused by Chad's unusual antics, standing idly by while Melissa argues with him. When Chad made the suggestion that the punch was blood, Zack briefly pretended it was true to show how ridiculous that was. In spite of this, he was quick to go along with Chad's 'Vampire-hunter' theory and went 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. 

Balthazar Cavendish and Vinnie Dakota

While Zack doesn't know them very well, he is on friendly terms with Cavendish and Dakota. Initially, he assumed, thanks to Chad, that the two of them were vampire hunters, and this led to his confronting them at a school dance. This impression didn't last long, and eventually, they were formally introduced to him by Milo as time travelers.


Zack had a brief crush on the danger-seeking girl, and he forced aside his typical cautious attitude to impress her. He was attracted to her for less than a day before he realized how dangerous she was ("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.
  • He shares the same last name as Weevil Underwood from Yu-Gi-Oh!.
  • 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 who he claims can eat with their feet.
  • In Love Toboggan, it was shown he knows how to snowboard.