1985–1989

Timm's early career in animation started at Filmation, working on the layout of Blackstar, Flash Gordon, He-Man and the Masters of the Universe, its spin-off She-Ra: Princess of Power, and The Lone Ranger. He also did background work on G.I. Joe.^[6] He also worked for numerous other employers, including Ralph Bakshi and Don Bluth Productions, and attempted to find work at Marvel Comics and DC Comics, but was unsuccessful.^[7] During an animators strike in 1982, Timm found himself out of work and went back to Kmart for about half a year, before being hired by Don Bluth to help work on The Secret of NIMH. In 1987, he was hired by John Kricfalusi to do layouts for Mighty Mouse: The New Adventures, which Timm called "artistically and creatively the most fulfilling job that I'd had in the animation business" up to that point.^[8] He worked at DIC Entertainment on The Real Ghostbusters for one season in 1988, then joined Warner Bros. in 1989. At Warner, Timm worked on Tiny Toon Adventures.^[9]

1992–2006

Timm was one of the creators and producers of the animated series based on various DC Comics superheroes, known as the DC Animated Universe. The DCAU has also named the "Timmverse" or "Diniverse", after both him and Paul Dini, a writer and producer.^[10] Along with his Tiny Toons partner Eric Radomski, Timm co-created and produced the Emmy Award-winning Batman: The Animated Series, which premiered on September 5, 1992, through which he and Dini co-created the character of Harley Quinn, and went on to co-create and produce Superman: The Animated Series (premiered in September 1996), The New Batman Adventures (premiered in September 1997), and Batman Beyond (premiered in January 1999), through which he and Dini co-created Terry McGinnis, the teenage Batman of the future, and his supporting cast.^[11] Timm worked as an animator and character designer on the feature-length Genie by Mistake (1999). He also served as producer on the feature-length Batman Beyond: Return of the Joker (2000)^[12] before taking the helm as creator and producer of the animated version of Justice League, which debuted in November 2001; the series continued in the form of Justice League Unlimited in July 2004.^[13] Timm was also the producer and creator of Green Lantern: The Animated Series (premiered in November 2011).^[14] Along with Dini he created the animated series Freakazoid! (premiered in September 1995).^[15]

Timm created virtually all the original character designs for Batman: The Animated Series himself, with the exceptions of Mr. Freeze and the Riddler, who were designed by Mike Mignola, and the characters Man-Bat and the Mad Hatter, who were designed by Kevin Nowlan. He shared character designer duties on Superman: The Animated Series and Justice League with James Tucker.^[16]

2008–present

The 2008 project Batman: Gotham Knight is a departure from the "Timmverse" style, with Timm in a producer role collaborating with Japanese animators on a direct-to-DVD anthology that takes place between the live-action Batman Begins (2005) and The Dark Knight (2008) films.^[17] In 2013, following the release of The Dark Knight Returns animated feature, Timm stepped down as DC animation supervising producer; James Tucker was named as his replacement.^[18] Timm still works at Warner Brothers, and executive produced the DC Universe Original Animated Movies^[19] Justice League: Gods and Monsters (2015)^[20] and Batman: The Killing Joke (2016),^[21] and series Justice League: Gods and Monsters Chronicles (2015).^[22] He was a writer and executive producer for Batman and Harley Quinn (2017).^[23]

Timm worked with Man of Steel director Zack Snyder in creating a 75th anniversary short of Superman in 2013.^[24] In 2014, he released Batman: Strange Days, an animated short celebrating the 75th anniversary of Batman and an homage to one of Hugo Strange's first appearances in the comic books.^[25]

During DC FanDome 2021, Timm was announced to be executive producing a new Batman animated series titled Batman: Caped Crusader alongside J. J. Abrams and Matt Reeves. Comparing the new series to Batman: The Animated Series, Timm stated, "There were certain limitations on what we could do in terms of adult content; in terms of violence and adult themes. My idea is basically to say, 'OK, it's 1990 again, I get to do what I want to do this time, and I got JJ and Matt backing me up.'"^[26]

Acting

Timm has played several characters in the animated series he has been involved in. His cameos include the 1992 episode of Batman: The Animated Series, "Beware the Gray Ghost", playing the toy shop owner,^[27] as himself in the 1997 episode of The New Batman Adventures, "Holiday Knights", and as the leader of the Jokerz gang in Batman Beyond, which he joked he did under duress and was "Emmy Award-winning material".^[28] He subsequently appeared in an animated form in the 2009 episode of Batman: The Brave and the Bold, "Legends of the Dark Mite", in a comic book convention parody scene, in which he wore Joker's costume, alongside Paul Dini in Harley Quinn's costume.^[28] He played a guard in the 2000 direct-to-video animated film Batman Beyond: Return of the Joker.^[29]

Timm made a cameo appearance in the 2009 film Green Lantern: First Flight as Bug Boy. He played The Riddler in the 2010 film Batman: Under the Red Hood and appeared as Galius Zed in the 2011 film Green Lantern: Emerald Knights.^[30]