The Thundercats also existed as a comic book during the 80's. Star Comics produced 24 books before interest in the series was lost. The story lines and art in the books was very similar to the TV series. These books aren't worth much on the market, but are still valued and sought after by fans of the series.
The Thundercats comics have been revived recently by WildStorm comics. A 5 book mini-series has been completed, and new 5 book mini-series (The Return) is being published now. The art and storylines in these books is much more adult-oriented than the original comic or TV series. There's more skin, more graphic violence and the clothing (or lack thereof) has been updated.
However, I think the new comic series suffers somewhat from having its roots in kiddie television of the 80's. For example, the names of the characters are too cute and don't seem to fit the more adult subject matter on occasion.
When Lion-o would call for the power of the Sword of Omens with "Thunder, Thunder, Thundercats, ho!" in the TV show, you knew it was time for Lion-o et al. to throw down. The anticipation, Lion-o's voice and the background music sent a little shot of adrenaline to your 8-year-old heart. But in the comic book, the effect is lost. When I was a kid, I never thought: well, why don't the bad guys just rush him while he's doing that bit with the sword? But as an adult, it was first thing that crossed my mind.
That said, I'm still a fan of Thundercats new and old. The new comic series has enough nostalgia value to remind me of what it was like when I was a kid, but has been updated enough that my adult side is interested.