The phrase "ass character" is often used to describe someone who has a negative or unpleasant personality. It refers to a person who is selfish, rude, or disrespectful towards others. Full definition
Black Panther is not all just impressive gadgets and kick ass characters, though. (firstshowing.net)
A common movie trope is where a bad ass character starts walking toward a hail of bullets, picking people off while the bullets miss him entirely. (sbnation.com)