Batman
The Sword of Omens is pretty much the bat signal when used to call to the other Thundercats for help.
Other similarities between Batman and the Thundercats:
Special vehicles: Batman has the Batmobile, the Thundercats have the Thundertank.
Hi-tech headquarters: Batman has the Batcave, the Thundercats have Cats Lair.
Loyal servant to orphaned hero: Batman has Alfred, Lion-O has Snarf.

How bout "Teenage Mutant Ninja Turtles?"
The Thundercats were created before the Teenage Mutant Ninja Turtles. TMNT was conceived in part as a parody of Marvel's
Daredevil
comics. In the original TMNT comics it was implied that the radioactive waste that mutated the Turtles was the same that blinded young Matt Murdock. Daredevil was trained by a sensei named Stick while the Turtles were trained by a sensei named Splinter. Daredevil fought a ninja clan called the Hand while the Turtles fought a ninja clan called the Foot.
Besides
Star Wars
,
Superman
, and
Batman
being possible inspirations for
Thundercats
, I'd include
Planet of the Apes
and other series such as
Kamandi
and
Thundarr the Barbarian
that featured highly evolved animals and savage humans on a post-apocalyptic Earth. While it was never explicitly stated that Third Earth was our planet sometime in the future, there are clues suggesting that it was.

How bout "Teenage Mutant Ninja Turtles?" Nuff said with Mumm-Ra and Shredder I guess!

http://scifiblogs3.blogspot.com/

• • Sci-fi, Batman, and E:FC

http://www.childrenofrassilon.com/

• • Homage to DW & B7

Batman
The Sword of Omens is pretty much the bat signal when used to call to the other Thundercats for help.