1960s Batman TV series, who is later replaced by Richard Green after Gorshin's death), is portrayed as a secondary character in the season. The characters Yin and Police Chief Rojas make their final appearances at the end of the season. Season 3 In the third season, the show introduces a younger incarnation of Barbara Gordon (voiced by Danielle Judovits), who is the police commissioner's daughter. Over the course of a two-part story, she secretly becomes Batgirl. The show's opening title sequence changes this season, and the opening theme music (performed by U2 guitarist The Edge) is substituted with a lighter, '60s theme performed by Andy Sturmer. Throughout season 3, Barbara tries to become Batman's sidekick and be as good of an ally as her father. However, Batman frequently refuses to accept her help, although she proves herself to him by the end of the season. This Batman-Batgirl storyline differs from the comic books. In previous incarnations of the story, Batman's first partner is Dick Grayson, who becomes Robin and joins Batman as his apprentice, later leaving to become Nightwing. The decision for Batgirl to be Batman's first sidekick in The Batman was due to Robin not permitted to be used in the show due to him being used in the Teen Titans animated series, which aired on Cartoon Network and due to the Bat-embargo (a restriction in place regarding usage Batman's allies and enemies in multiple animated shows based on the comics). This season also sees the destruction of Batman's original Batmobile, which is replaced by an updated version for the remainder of the series. Several more new villains from the Batman mythos are introduced this season, including Poison Ivy (voiced by Piera Coppola), a different version of Gearhead (voiced by Will Friedle), Maxie Zeus (voiced by Phil LaMarr), the Toymaker (voiced by Patton Oswalt), Prank (voiced by Michael Reisz), Temblor (voiced by Jim Cummings), and D.A.V.E. (voiced Jeff Bennett). Hugo Strange becomes a villain this season, having orchestrated the events of "A Fistful of Felt" and "Gotham's Ultimate Criminal Mastermind." The season finale concludes with his incarceration at Arkham Asylum. Season 4 With the conclusion of Teen Titans in 2006, the fourth season introduces Dick Grayson (voiced by Evan Sabara). The opening episode of the season focuses on Dick Grayson's origins as Robin. Through the loss of Grayson's parents in a murder made to look like a circus accident,