Javier Jimenez was the cousin of Boaz Jimenez and the leader of the Death Squad out of Juarez. He later became a sicario for Teresa in New Orleans.
Herrera’s character, Javier Gallegos, is described as a hired gun who’s willing to kill. A cousin of Boaz Jimenez, Javier is a longtime member of the Jimenez organization who rides a motorcycle, enjoys the company of ladies, and isn’t one to turn down a good time.
- Justicia: Javier works with James to recover King George from Cortez's fortified compound.
- El Mundo: In Phoenix, he and Boaz torture Cortez in order to get the location of Camila. He is present when King George kills Cortez in revenge for lobotomizing Bilal. When James expresses his interest in leaving, Javier remarks that James will be a hard soldier to replace. Javier is one of Teresa's underbosses in her business now and he leaves for New Orleans with her.
- Bienvenidos a Nuevo Orleans: Javier warns Boaz that his behavior is causing people to suspect him of disloyalty. He reminds boaz that in this business they are all replaceable.
- Un Asunto de Familia:
- Hospitalidad Sureña: After growing frustrated with René's continued racist and disrespectful comments toward himself, Boaz, and Teresa, Javier beats him up and drowns him in the toilet of the club's bathroom.
- La Maldición: Boaz and Javier attempt to get rid of the two men they killed in the previous episode. When dumping the bodies in a swamp, they are seen by a birdwatcher, who they attempt to track down. Javier and Boaz are able to talk a little bit while hunting the man. Teresa worries when she can't get ahold of them and thinks the worst.
- Noche de las Chicas: Teresa scolds Javier for being unreachable. She tells him to bury Bobby and send Boaz back to Mexico for his behavior, telling Javier that if he's going to behave the same way, he can leave too. Boaz does want Javier to go back to Sinaloa with him.
- La Mujer en el Espejo: Teresa discovers Emilia at Javier's place. He warns her that Boaz can't know that she's here. Teresa later has Javier drive her to Eddie's place, so they both know about each other's secret lovers. She asks if he's in love with Emilia. He says it wasn't planned. Teresa asks him to put a man on her 'friend' for protection, but he can't know. Javier discovers that Cedric is the mole and has been leaking information to Randall Green.
- Amores Perros: Javier realizes that the man he killed in the bathroom was the Judge's nephew after seeing Randall make an appearance on TV. Javier kills the junkyard man after he sees the blood in the back of his Lincoln. Emilia witnesses this murder and it shakes her. Javier also kills a cop who pulls them over. Emilia is upset with Javier as he sets fire to the Lincoln to destroy evidence.
- Secretos y Mentiras: Javier volunteers to go into the prison.
- Vienen Por Ti: Javier visits Emilia's gravesite and grieves. Teresa and Pote learn that Javier is responsible for Tony's death. Javier sets both himself and Randall on fire and they die.
- Boaz Jimenez: After Camila decides she wants him dead, Boaz goes into hiding by meeting up with his cousin Javier. In Season 4, Javier repeatedly tries to get Boaz to behave so that Teresa doesn't decide to replace him. This endeavor, however, is complicated by their murder of René Bardot.
- James Valdez: James and Javier work together to recover King George. Javier thinks that James is a good soldier and acknowledges to Teresa that James saved his life. It is implied that they have met before and have some history.
- Teresa Mendoza: He decides to follow Teresa after James leaves at the end of Season 3. In Season 4, he serves as her sicario and bodyguard, as well as one of the underbosses in her business.
- Pote Galvez: Javier serves as a sicario and bodyguard alongside Pote in Season 4.
- Randall Green: Javier seeks revenge against Randall for killing Emilia. His thirst for revenge is so strong that Javier kills himself in the process.
- Are we crazy? To want something different in this life? 
- Mijo, I lost my wallet, but I brought some famous politicians to vouch for me. You know Ben Franklin?