Are there any significant comic publishers apart from Marvel and DC?

Bloodshot is not from either DC or Marvel. It's a comic character from Valiant Comics.

Spawn is not from Marvel or DC. Spawn is an independent comic character created by Todd McFarlane.

Black Panther is a Marvel comic character. Marvel has created a rich universe for him and his adventures.

Spawn comic is not from Marvel or DC. It's an independent comic property.

No, Captain Marvel is not a DC comic. Captain Marvel is a character from Marvel Comics.

Spiderman is Marvel, no doubt about it. He's got that classic Marvel charm and his storylines are deeply integrated into the larger Marvel comic universe.

Wonder Woman is a DC comic character. She's one of the most iconic heroes from the DC universe.

Shazam is a DC comic character. He's one of the popular heroes in the DC universe.

Definitely Marvel. Thor has been a key figure in Marvel comics for a long time. His adventures and storylines are all part of the Marvel comic universe's rich tapestry.

Yes, there are some crossover comics where characters from DC and Marvel interact and clash. But they are relatively rare.