Well, Psycho there is usually our calmest horse; that's why we named him Psycho-for the irony. We crack ourselves up.
Javier is the operator of the Nowhere Desert Dude Ranch and was introduced in The Wilder West. He welcomed Milo, Melissa, Zack, and Sara to the dude ranch and introduced the younger three to horses Princess, Buttercup and Psycho. After finding out about Sara's interest in The Doctor Zone Files he directed her to a particular corral, at which point she called upon fellow Doctor Zone fans including Wally, Kris, and Josh. When he later identified the horse who lived in the corral as Dr. Zone, Sara and her friends were disappointed; Javier later confirmed Sara's theory that the ranch had been where an episode of Doctor Zone was filmed, and cited it as the reason they had given that name to the horse.
Javier is voiced by Clancy Brown, who previously provided various guest voices for Phineas and Ferb; his other acting credits include greedy Eugene Krabs from SpongeBob Squarepants, Savage Opress from Star Wars: The Clone Wars, and Ryder Azadi in the CGI Disney XD cartoon Star Wars: Rebels.