Advocacy group Autism Speaks is launching its second annual Sound Off for Autism charity, which uses celebrity star power to raise money for autism research and awareness. This year’s lineup includes a who’s who of geek culture’s favorite stars hailing from Star Wars, Star Trek, Game of Thrones and Big Bang Theory. Celebrities participating in the charity have offered to record a limited number of custom audio messages to charity backers in return for a $299 donation.

After William Shatner, Leonard Nimoy, Patrick Stewart and Carrie Fisher’s involvement last year, the sci-fi universe is again well represented. Star Trek’s Zachary Quinto and Michael Dorn are participating this year, as is Mark Hamill from that other popular sci-fi galaxy. TV favorites include Bryan Cranston, Peter Dinklage and Jim Parsons. Also participating are Adam West, Cher, Jack Black and Vin Scully. The geek cred angle notwithstanding, the clear theme among these stars is notoriously recognizable voices. On that note, the first to sell out at the time of this writing is L.A. Dodgers broadcasting legend Vin Scully.

Autism Speaks estimates that autism affects nearly one in nine children in the U.S., making it one of the most serious afflictions in this country. The condition has also spiked in recent years – up by 79 percent over the past six years – which charity organizers attribute in large part to better diagnosis in young children.  The organization’s Sound Off program was founded in 2012 by legendary TV actor Ed Asner, raising more than $100,000 from the aforementioned Star Trek-Star Wars crew along with Tom Hanks, Morgan Freeman, Will Ferrell, Betty White and Derek Jeter.

The fundraising drive offers a limited number of audio messages from each celebrity on a first come, first serve basis. For more information and to donate, please visit the Sound Off for Autism web site.