Ellis, best known for playing the flamboyant Lafayette Reynolds in the horror-drama series, died after complications from heart failure.
"He was a great talent, and his words and presence will be forever missed," his manager Emily Gerson Saines told the Hollywood Reporter.
Ellis appeared in True Blood from 2008 until the series ended in 2014.
"We were extremely saddened to hear of the passing of Nelsan Ellis," HBO said in a statement on Saturday.
