The bulldog that often chases Tom is named Spike.
Spike is a stern, powerful bulldog who frequently becomes involved when Tom’s schemes disturb him, threaten his bone, or bother his puppy son, Tyke. Jerry often exploits Spike’s temper by provoking trouble and leaving Tom to take the blame. This creates a recurring three-way pattern: Jerry causes the mischief, Tom is caught nearby, and Spike retaliates against Tom.
Spike first appeared in Dog Trouble, a 1942 theatrical short, where he was an unnamed bulldog. He was initially mute and attacked both Tom and Jerry rather than acting as Tom’s consistent enemy. Later shorts developed him into the recognizable character called Spike.
Some cartoons and reference materials use names such as Killer or Butch for versions of the bulldog, which can cause confusion. But Spike is the standard canonical name associated with the recurring bulldog, while Butch is more commonly the name of Tom’s black alley-cat rival.