Look, I know this might be "obvious" to most of you guys but I've only seen him in Evolution and in Runaways, and occasionally when he guest stars in some of the shows I watch. But how in the world did you guys link Zamasu's voice immediately with James Marsters? And why? Do you guys hate James or something and think he is a terrible actor with a terrible role? I mean seriously, why would James be in a franchise that ruined his career?
He was first hinted at by one of the Xenoverse cast members who compared the casting for Xenoverse to Seychelle Gabriel (who played Yue in Last Air Bender - the shitty live action version) being cast in Legend of Korra. Then people noticed Zamasu's voice sounding just like Marsters and kept trying to find confirmation.
He seems to be using a pseudonym for legal reasons but it's him. His Xenoverse pseudonym is Sam Majesters which is a literal anagram of James Marsters.
For what it's worth, when James Marsters was cast in Evolution, he watched DB to study up on his character. He ended up liking it and becoming a fan, and reportedly gave off a furious protest about his character's movie design being unlike the original
^Apparently the movie's failure hasn't particularly changed that fact. He voiced Zamasu in Xenoverse 2 under the above pseudonym, and 'David Gray' may or may not be him as well, based on the preview dub voice for DBS's Ep. 53