Writing '' artist
Lee Knox Ostertag Mulligan and
Lee Knox Ostertag co-created the webcomic
Strong Female Protagonist, which was named one of
io9's Best New and Short Webcomics of 2012. In 2017, Mulligan joined
CollegeHumor as a writer for
Um, Actually: The Web Series. In 2018, CollegeHumor's streaming service
Dropout launched
Um, Actually as a game show, with Mulligan continuing to write for the show until 2020. Mulligan was also a writer for several scripted shows on Dropout, including the
Star Wars parody space saga
Troopers, and the mockumentary
Gods of Food.''
Performing In his twenties, he performed and taught He has also appeared on other Dropout shows such as
Very Important People and
Gastronauts. In March 2026, Mulligan was a guest in "
Dungeons & Dealers" for the television series
Ted (2024); Mulligan helped rewrite the episode on set. That month, Mulligan also appeared on the new web series
Jeopardy! YouTube Edition as a contestant.
Actual play during the 2024 UK and Ireland tour Since 2018, Mulligan was the
Dungeon Master for
Exandria Unlimited: Calamity, a weekly, four-part
actual play web series
spin-off of
Critical Role that premiered on May 26, 2022. He returned to
Critical Role in 2024 as the Dungeon Master of the three-part special titled "Downfall" for the show's
third campaign. Mulligan was then the Dungeon Master for
Exandria Unlimited: Divergence which premiered on February 13, 2025. In January 2023, it was announced that Mulligan, along with
Erika Ishii,
Aabria Iyengar, and
Lou Wilson, would star in the creator-owned actual play podcast
Worlds Beyond Number. The show launched on March 1, 2023, and quickly became one of the top 20 Patreon accounts in the world; Mulligan was the "inaugural game master". The first book of this campaign ran for four seasons with the finale airing in August 2025. The next campaign premiered in March 2026 with Iyengar as the game master and Mulligan shifting to a
player-role. In August 2025,
Critical Role announced that Mulligan would take over as Game Master from
Matthew Mercer for their
fourth campaign. The new campaign premiered on October 2, 2025 and features a new world "outside its usual Exandria setting".
Rolling Stone stated that "the inclusion of Mulligan is huge, but not entirely surprising" given Mulligan's background as "a well-established Game Master" who created the "titanic success"
Dimension 20 along with previous comments made by Mercer on eventually shifting "into a '
Professor X' role as a mentor to the next generation of storytellers rather than remaining the face of the brand in perpetuity". Also in October 2025, Mulligan was the Dungeon Master for the
Endless Dungeon tour in Australia. == Accolades ==