Early career

He began his career as an assistant to director Michel Gondry, on his 2001 comedy Human Nature; as well as serving as cinematographer on Gondry's The Work of Director Michel Gondry. In 2005, he was hired as a story editor on the Kristen Bell fronted series Veronica Mars. He would later go on to serve as executive story editor, writing for fifteen episodes over the course of the shows run.

In 2007, he joined the new NBC series Chuck, as producer and writer. It revolved around a hapless computer nerd that inadvertently downloads top-secret info into his brain, and is then exploited by the government. Klemmer rose to be supervising producer, then co-executive producer for the series' last two seasons. He contributed to a total of 14 episodes.^[2] While simultaneously holding his position on Chuck, Klemmer also became a co-executive producer and writer for the short lived J. J. Abrams produced espionage drama Undercovers. Writing episodes "Jailbreak" and "The Key to It All".

2012–15

After Chuck's conclusion, Klemmer joined the writing staff of Greg Berlanti's USA Network miniseries Political Animals; as well as serving as consulting producer. He contributed to installments "The Woman Problem" and "16 Hours". In 2013, he continued his relationship with producer Berlanti, co-executive producing, showrunning, and writing for CBS's Golden Boy. The series was canceled after one season. Next, he developed a reboot of the British series The Tomorrow People for Berlanti and The CW.^[3] And the next season, joined the ABC drama Forever, created by Matt Miller, as showrunner and consulting producer.^[4] Both shows were cancelled by their respective networks after one season.

Legends of Tomorrow

In 2015, Klemmer was brought on the Arrow and The Flash spin-off, Legends of Tomorrow as executive producer and showrunner by creator Berlanti.^[5] The series follows a ragtag crew of heroes and villains who travel through time attempting to foil the maniacal Vandal Savage. When speaking about running the series Klemmer stated, "I really think that seeing Clash of the Titans when I was a little kid...I think that the reason I became a Classics major was because of Indiana Jones. And doing this show, which has that intersection of Vandal Savage...that is my sweet spot, where its history mixed up with the mystical, mixed up with...time?"^[1]

Film

Television

The numbers in writing credits refer to the number of episodes.