"So, based on info I got today, I'm gonna confirm Alec Baldwin as Dennis in Rock Of Ages. Hollah," EW.com said director Adam Shankman tweeted during the weekend.
The entertainment Web site described the character of Dennis as an "aging rocker who stays in the game by running a Hollywood club."
An 11-time Emmy nominee, Baldwin has won two Emmy Awards for the NBC comedy "30 Rock." He has won five Screen Actors Guild Awards for his work on the show, and was nominated for a supporting actor Oscar for "The Cooler" in 2003.