Brett Gelman

Gelman's father was a photo salesman. He was raised Jewish and has a younger sister who is a speech pathologist.

Gelman graduated from Highland Park High School in Illinois. He graduated from the University of North Carolina School of the Arts, where he received classical training in theater.After college, Gelman moved to New York City with a fellow schoolmate, actor Jon Daly. While in New York, Gelman was a regular performer at the Upright Citizens Brigade Theatre, as part of the duo Cracked Out and sketch group Mr. A$$.

A popular New York Lottery commercial funded his work for a while. Gelman did a one-man show called 1,000 Cats, which he workshopped at many venues.

Gelman has appeared in the films The Other Guys and 30 Minutes or Less. He has co-starred as Chris Elliott's sidekick Brett Mobley in the live-action Adult Swim series Eagleheart and is a regular sketch performer on HBO's Funny or Die Presents and Comedy Central's Nick Swardson's Pretend Time. He has had recurring roles on The Life & Times of Tim and The Inbetweeners, as well as making guest appearances on comedy programs such as Bored to Death, Curb Your Enthusiasm, The Office, Happy Endings, Aqua Teen Hunger Force, and The League. Gelman has also written for the MTV sketch series Human Giant and the Scott Aukerman & B. J. Porter created sketch pilot The Right Now! Show.

In 2010, Gelman appeared as a cast member on the Comedy Central sketch comedy special This Show Will Get You High, created by Matt Besser. Gelman co-starred as "Mr. K" on the NBC comedy series Go On starring Matthew Perry, and as A.J. on the FX comedy series Married.

In 2014, Gelman hosted a dinner party special, called Dinner with Friends with Brett Gelman and Friends, which aired on Adult Swim.

In 2015, Gelman was also a consulting writer on season two of the entertainment news parody series Hot Package on Adult Swim and also recurs as Hamish on the Comedy Central series Another Period and as Ronnie on the Starz series Blunt Talk. Also in 2015, Gelman appeared in the series finale of Mad Men.

In July 2016, Gelman starred in the special Dinner in America with Brett Gelman, a sequel to Dinner with Friends with Brett Gelman and Friends, which focused on racism. In November 2016, Gelman said that he had left Cartoon Network and Adult Swim due to the network's alleged poor treatment of female employees and the promotion of the controversial Million Dollar Extreme Presents: World Peace.

In 2017, Gelman starred in and co-wrote Lemon, opposite Judy Greer, Michael Cera, Nia Long and Gillian Jacobs, directed by Janicza Bravo. It had its world premiere at the Sundance Film Festival on January 22, 2017.

In 2016, it was announced that Gelman was cast in the second season of the hit Netflix science-fiction web series Stranger Things as Murray Bauman, a conspiracy theorist and former journalist. He was promoted to the main cast for the fourth season.

In 2018, he starred in the independent feature film Room for Rent, opposite Mark Little, Carla Gallo, Stephnie Weir, Patrick J. Adams, and Mark McKinney. Gunpowder & Sky released the film in the US on all major VOD platforms November 2, 2018.

In 2022, it was announced that Gelman was starring in the Apple TV+ drama series Lady in the Lake, based on Laura Lippman's novel of the same name.