Spike

Spike Bulldog is a grey, rough bulldog that appears in many of Tom and Jerry cartoons. He has a somewhat minor friendship with Jerry and is a fomidable enemy to Tom, though he is occasionally is a rival to both protagonists, as he was in the cartoon Dog Trouble.

Spike has a grudge against Tom, not just because he's a cat, but because whenever they cross paths, Tom is interrupting quality time with his son, Tyke because he's too busy chasing Jerry to watch where he's going. Obviously, whenever Spike tells Tom not to do a certain thing (ex. dirty Tyke), Jerry does his best to get Tom in trouble (in the example, Jerry would get Tyke as dirty as possible). After Spike beats Tom, he is shown having a good time or resting peacefully with his son tyke along with Jerry the real saboteur and culprit. Spike also appeared in some of the recent cartoons featuring a basset hound called Droopy, another popular MGM cartoon character.

Spike (and his son, Tyke) is most likely a secondary or even major character, as he has appeared in almost all renditions of Tom and Jerry's cartoons.