He was voiced by Hart Bochner.
Batman: Mask of the Phantasm
Reeves was initially the personal assistant of Carl Beaumont, however, he would betray Beaumont to Valestra's gang in order to gain the influence to enter City Council, and told them where his former boss was hiding in return for campaign funds, resulting in his eventual death. Years later, a vigilante known as the Phantasm started killing associates of Valestra, causing Reeves to have the police hunt Batman, thinking he was committing the murders. Although appearing as if he wanted Batman to be brought to justice for his supposed crimes, Reeves was actually worried that Batman would go after him and that he would lose money if that happened.
Despite their efforts, Batman succeed in evading the police, enraging Reeves. Joker eventually tracks Reeves down to his office, believing him to be the Phantasm, as he knew about the mob and sold Carl out to them. During their confrontation, Andrea called and Joker realized that she was actually the Phantasm, and poisons Reeves with with Joker venom, no longer having a use for him.
Reeves later appears in the Gotham City Hospital, having been driven insane by the Joker's chemicals. Batman confronts Arthur and demands to know why Joker visited him. Reeves then tells Batman of his connections to the mob, although does not give him any information regarding the Phantasm, as he didn't know her identity. Batman leaves Reeves, denying him curing as punishment and leading the doctors to come to the room to sedate Reeves once more. It's completely unknown what happened to Reeves afterwards, but as it's implied that only Batman knew the cure for his condition, it may be possible that Reeves' condition worsened until he eventually died or that he spend the rest of his days in complete madness unless anyone was able to find an alternative cure for him. However, it's likely that in any case, Reeves' political career was ruined for his condition if not for his corruption.
The New Batman Adventures
Though Arthur Reeves doesn't make any appearance in the Batman: The Animated Series follow-up show The New Batman Adventures, he makes a non-physical cameo in the episode "Beware the Creeper". In the episode, to celebrate the Joker's seventh anniversary after his fall into the chemicals that changed his life, Jack Ryder narrates a documentary about the Clown Prince of Crime's life, including facts about his early days as a hitman for the Valestra family, even showing one photograph in which Reeves appeared along the Joker, Chuckie Sol and Carl Beaumont. So, whatever Reeves' fate was, it's highly assumed that, even if he was still alive or not, Reeves' reputation as an honest politician was utterly destroyed either unknowingly or posthumously.
Arthur Reeves returns as main antagonist in the seemingly canonical Batman Adventures issue "Batman & Robin Adventures Annual #1". However, given that the comic book series contradicts several pieces of the established DCAU canon, it may or may not be non-canonical.
After Andrea's assumed death, Arthur was cured of his condition and Bruce sought to get information regarding her from him, however, he was of no help. To make matters worse, Arthur later suffered from an allergic reaction to the toxins Joker used on him, which forced him to smile at all times, driving him insane. Blaming Phantasm for what had happened to him, Arthur spent his resources seeking to discover the assassin's identity, eventually discovering that he was Andrea all along.
Seeking to get revenge, Reeves ordered the assassination of Bruce Wayne, knowing that Andrea would be drawn back out to defend her former lover. The attack succeeds in drawing Andrea out, as well as another by his henchman Kitsune, and Reeves has Andrea kidnapped while she is with Wayne at his mansion. After inspecting the Phantasm gear, Reeves reveals himself to Andrea as the mastermind behind her kidnapping and explains his motivation for wanting to have her killed. Before Reeves can have Kitsune slit Andrea's throat, Batman bursts in and begins fighting off the henchmen. Upon untying Andrea, Batman is smashed across the head by Reeves using Phantasm's claw before doing the same to Andrea. Reeves pulls off the unconscious Batman's mask and, realizing that Batman and Bruce Wayne, two men who had "put him through hell" are the same person, prepares to slit his throat, only to be kicked back by Andrea. Andrea dawns her Phantasm outfit again and Reeves madly lunges at her, only to find that he is attacking the costume, plunging off the balcony to his death.
Reeves was quite a selfish, arrogant young politician who, although seemingly in love with Andrea Beaumont, let her father get killed by a hitman who would later be the Joker. Reeves was not only corrupt and a puppet to the mob but was also quite nervous and anxious when his life would be threatened. He began to sweat and pant when the Joker was threatening his life, proving that he clearly was scared and desperate for his life. He would do anything to save himself and did not care about what would happen to others.
- While Arthur Reeves' mainstream comics counterpart was never the nicest individual (vehemently opposing to Batman's vigilantism), he was largely regarded as comic relief instead of a genuine villain. Up until his appearance in Batman: Mask of the Phantasm, after his initial debut, Reeves was featured as running for mayor on an anti-Batman platform, but would ruin his own campaign by publicizing hoaxed photos from Rupert Thorne which depicted Batman as a mob boss, leading Reeves to retire from politics in disgrace. His incarnation of the DC Animated Universe, however, is more selfish and arrogant who, despite his initial kindness, backstabbed his former boss in exchange for the necessary money to finance his political campaign despite possibly knowing Salvatore Valestra's intentions and ordered a manhunt against Batman without proofs that he was killing Valestra's mobsters just for the sake to not lose his money, making this version of the character far worse and darkest than his mainstream counterpart.
- Ironically, in the comics, the candidate who ran for mayor against Reeves and ended up wining due Thorne's intervention was none other than Hamilton Hill, who was corrupt in comic book continuity and on Thorne's payroll, whereas the DCAU incarnation of Hill is never depicted as corrupt but rather as an effective law official, being represented as the contrary he was in the comics in a similar vein to Reeves. Coincidentally, Hart Bochner, the actor who voiced Arthur Reeves in the film, is the son of the late Lloyd Bochner, who voiced Mayor Hill in Batman: The Animated Series and The New Batman Adventures.
- Despite meeting his ultimate fate in Batman Adventures, since the series is debatably non-canon to the DC Animated Universe, it is possible that Reeves was never "cured" of Joker's toxins, meaning he is still poisoned, yet alive.