http://www.tracking-board.com/mark-hamill-ron-perlman-join-transformers-animated-series/
Hamill is no stranger to Transformers, as he previously starred in Transformers: Rescue Bots. He will now make his debut as Megatronus in the finale of the currently running series Transformers: Titans Return. Megatronus is the first Decepticon and was exiled from Cybertron after murdering one of the other original thirteen Primes.
Perlman will make his debut in the third and final chapter of the trilogy, Transformers: Power of the Primes, debuting this spring. He will be voicing Optimus Primal, the leader of the Maximal forces.
Other voice actors include Judd Nelson as Rodimus Cron, Will Wheaton as Perceptor, Samoa Joe as Predaking, Jaimi King as Solus Prime, and Rob Dyke as Devastator.
Transformers: Power of the Primes is being overseen by showrunner and executive producer FJ DeSanto, written by Adam Beechen, and directed by YUZO. Tatsunoko Productions is overseeing animation for the show.