Parks and Recreation executive producer Harris Wittels was pronounced dead around 1 p.m. by law enforcement officials, TMZ reported.
The 30-year-old was found on his couch by his assistant in his home near Los Feliz, the Los Angeles Police Department said.
An official cause of death must still be determined by the Los Angeles County coroner, but several industry publications, citing unidentified sources, reported that Wittels may have died of an overdose.
Wittels had spoken previously about his struggle with drug addiction and had gone to rehab twice.
Wittels had written for Parks and Rec since the show started in 2011 and had appeared in several episodes as an animal control employee.
In addition to Parks and Rec, Wittels had worked on Eastbound and Down, The Sarah Silverman Program, and Secret Girlfriend.
Parks and Rec is in its final season and will air its last episode Tuesday.
He also popularized the humblebrag, which became such a huge phenomenon Wittels turned it into a book, Humblebrag: The Art of False Modesty, in 2012.
Wittels performed stand-up comedy and had reportedly told a bit about being clean and sober Wednesday night at the Meltdown, a Los Angeles comedy venue.
Many who knew Wittels took to Twitter to express their grief:
Amy Poehler said Thursday night that she "lost a friend. I lost a dear, young friend in my life who was struggling with addiction.”
She was being honored with the Unity Award at Variety's unite4humanity event, when she took a moment to to speak about Wittels.
"I'm sharing it with you because life and death live so close together, and we walk that fine line everyday. When things happen in our lives, we turn to the people that we love…and we lean on people, in a hope that we will ease our pain," she said.
"So, I don't really feel like telling any jokes. I'm kind of sad, and it's really great to be here tonight and listen to all of you, and listen to the great work that you do and be reminded why we live in this bizarre planet called 'Hollywood.' It's very strange."