Which cartoon premiering on May 26, 2013 features Liam O'Brien as a voice actor.
Liam O'Brien:  In cartoons, he voices in shows such as "Star Wars Rebels", "", "Avengers Assemble", "Wolverine and the X-Men", and "Hulk and the Agents of S.M.A.S.H.". Avengers Assemble (TV series):  Designed to capitalize on the success of the 2012 film, "The Avengers", the series premiered on Disney XD on May 26, 2013, as the successor to "".
Avengers Assemble