Clancy Brown will be voicing Grune the Destroyer, while Robin Atkins-Downes will be voicing Mumm-Ra! Check out some of his voice work here: http://www.robinatkindownes.com/#/voiceover
Looks like we have most of the major characters covered, voice wise. Could Jim Meskiman be one of the mutants…or perhaps Jaga?
the Kurgan is gonna be Grune? that’s kinda cool. lol
Don’t know the other guy. One of the voices under “voice match” kinda sounded like Captain Shiner tho. shrugs
the closest thing to Mumm-Ra I hear is his “creatures” section. 
Wow. Just looked both of their IMDB profiles up and they’re… impressive, to say the least. The Mumm-Ra voice-actor has twenty one years of experience under his belt and, in 2006 alone, had about a million things going on.
Voice-acting wise, they’re names. Both characters are tough to pull off but I’m hoping they bring something different, voice wise, to the table. This should be a re-imagining and trying to create an entirely different, fresh look to ThunderCats - we know how awesome the original series is so that won’t be affected regardless. But I’m liking this. Lots.
Listening to Jaga in the trailer, I am close to believing that is Jim Meskiman 
I might be totally wrong, but given the voices I’ve heard him do…it sounds like him.
Both voices are very good. Robin Atkins-Downes is very experienced and this is what was needed for an ancient wizard!
I believe that Jaga is voiced by Corey Burton, who voices Count Dooku in Star Wars: The Clone Wars.
I agree. I watched the new trailer and thought I was watching a Star Wars Clone Wars clip at first. Found a clip for non-Star Wars people. In case you can’t tell by the voices, Dooku is the one sitting, meditating in this clip: http://www.youtube.com/watch?v=bkwX_YM5AuY
I’m liking the voices and animation so far!!
Clancy Brown as Grune = EPIC WIN!!! :D:D:D
I think I called this one, too! 
I’ll take Robin Atkin-Downes (no pun intended) as Mumm-Ra. He’s a very versatile voice actor, and I’m sure I’ve got more than a few video games in my library that feature his talents (particularly the Bioware titles). But the role I remember him for the most was on Babylon 5, where he played the leader of a band of fugitive telepaths named Byron who sought asylum on the station in its 5th and final season. And considering he’s very capable of playing a villain like Baron Zemo on The Avengers, I’d say he has the chops to do Mumm-Ra!
Lex Luthor is voicing Grune the Destroyer??? Totally on board with that.
I have no idea who the guy voicing Mumm-Ra is. Hopefully he’s good because that is obviously a key character to get right. The original voice was beyond perfect (God Bless Earl Hammond) so I’m trying not to set my expectations too high.
i have read on wikipedia that Corey Burton is voicing Slythe
The Kurgan as Grune? You know what? That makes sense.
Agreed Clancy is a good choice
According to imdb.com Dee Bradley Baker is voiced as Slythe. He also voiced Appa/Momo in Avatar so maybe he is voicing Snarf in the series, that would be great!
I agree. He’ll be a great voice for Grune.
imdb.com are now saying that Jim Meskimen will be voicing Jaga
Merged Post:
OOPS meant to put Corey Burton is showing as the voice of Jaga on IMDB.com
I popped in SSD to just hear his voice again and yes, I think that is a good choice for Grune. As for Mumm-ras, well sadly I dont have anything with him in it but just looking at his credit list that guy does ALOT of voice acting…like..alot. So I’m sure that they are good choices.