Listen pussy cat, My boy is learning how to chase cats, and I Do want him to have any trouble. Understand? When he starts barkin', you start climbin'. Is that clear?
~ Spike The Bulldog in That's My Pup
Spike the Bulldog is the anti-heroic tritagonist of the animated series Tom and Jerry. Though he is sometimes a protector of sorts towards Jerry Mouse, his son, Tyke and sometimes Tom such as in "The Truce Hurts", sometimes going as far as being an enforcer of sorts to the mischievous rodent - however there is no denying that Spike is often unjustly cruel towards Tom (a stereotype of dog/cat rivalry) and although he often gives Tom several chances to avoid his wrath he will attack the cat viciously once those chances have been spent.
Tom often tries to get revenge on Spike, so it can be argued that much like Jerry Mouse himself Spike can play both the good guy and the bad guy depending on the cartoon - in general though he is a bully in regards to Tom and threatens to harm the cat physically, to the point of making Tom fear for his life on numerous occasions.
Spike can also be friendly when he wants to be and is seen to be a caring father, showing that, although a fierce opponent he isn't entirely without merit.
Also Tom's fear of Spike is showcased in the fact that when he had a nightmare about having died he envisioned Spike as none other than Satan himself.
Ironically despite their close friendship nowadays in early appearances Spike was an enemy of both Tom and Jerry, with the cat and mouse occasionally teaming up to rid themselves of the aggressive beast: this element of Spike seems to have faded over time as he is now considered primarily Tom's secondary-nemesis (next to Jerry himself). In the Tom and Jerry Show in the 1970s, Spike was sometimes the rival to a basset hound called Droopy, another MGM creation.
In Tom and Jerry Kids, his personality is softer, but his animosity with Tom as a kitten (or Tom's Child) still existed as he threatens Tom.
In Tom and Jerry Tales he was voiced by Michael Donovan who also voices Sabretooth in X-Men: Evolution, Grey Hulk in The Incredible Hulk, Guile and Zangief in Street Fighter TV.
Many appearances consist of him threatening and sadistically harassing Tom despite either never being provoked or not even being his fault, even to the point of making the poor cat fear for his life.
In several episodes, he also even enslaves Tom (with Jerry joining the party).
He even antagonizes Droopy in The Tom and Jerry Comedy Show.
In his first appearance "Dog Trouble", he not only chases after Tom, but also after Jerry. Forcing the cat and mouse duo teaming up to fight back.
In "Pet Peeve", he tries to capture Jerry and competes with Tom in this. (Both get kicked out of the house anyways.)
In "The Truce Hurts", let alone harrasing Tom as usual, it's one of the episodes where he eats Jerry, yet tries to have all the steak to himself. (In fairness Spike, Tom, and Jerry all fought for it. All three, return to their respective enemies).
In "Heavenly Puss", he is portrayed as a devil dog and lives in hell, where he manipulates Tom to be sent to hell so that he can torment him in boiling hot water.
In "More Powers to You", Spike is a super villain in this episode known as "Doom Dog", who the newly empowered Tom and Jerry team up to beat.
In "Tom-Fu", he is depicted as a passive-aggressive bully to Tom on a new level, with Jerry and Tuffy joining the party. Forcing Tom to practice kung-fu as self-defense to stand up for himself.
In "Tom and Jerry: Shiver Me Whiskers", he scares Jerry to death by shortly attempting to eat him, then attempts to steal the map to the Treasure of the Spanish Mane to himself. He successfully took advantage of Jerry for it, until Tom successfully managed to grab it by surprise. He thus enslaves Tom by the end as he takes full control of him after yet another accidental land.
In "Tom and Jerry: Blast Off to Mars", he terrorizes Tom and the whole town by repairing the Invincatron as he didn't even bother to sacrifice his bone to the fact that the town was in danger.
In "Tom and Jerry: The Fast and the Furry", he blindly harasses Tom by beating him and even choking him to death, which adds insult to injury onto the amount of destruction already caused onto Tom and Jerry's property. He then gets away with it all and has Tom framed for all of it despite being left in charge by his owner for an hour to take care of their home. Unlike the previous mentioned films however, Spike does fortunately end up getting his comeuppance as Tom's car lands on him, making the poor cat safe from another form of harassment that is otherwise lead by an accident that, as usual, wasn't Tom's fault to begin with.
In "Tom and Jerry: Willy Wonka and the Chocolate Factory", he assists Arthur Slugworth to obtain the Everlasting Gobstobber as the secondary antagonist and beat Willy Wonka in the candy-making business. At the end, he and Slugworth both get their comeuppance as they both get shrunk by Tom.
In "Quiet Please", he has an anchored sailor tatoo in his arm, ready to skin Tom alive after he was really being disturbed by Jerry who planted a dynamite stick beneath him.
His accent is similiar to famous comedian Jimmy Durante.
After he and his son was being bothered and messed up by Tom. Jerry was the next to bother and messing up them, so he could blame all of his troubles and disturbance that he put on them on Tom and Spike completely fall for Jerry's tricks and blames Tom.
In The Tom and Jerry Show 2014 Spike is no longer Jerry's friend, he finally realizes it was Jerry who was really causing all of the disturbance and the trouble had put on him, his son and Tom and also stealing his bones and messing up his son but sometimes he helps them to remove his tooth and his birthday party when he was upset.
He is friends with his son named Tyke, enemies with Tom, and "frenemies" with Jerry.
Though he isn't always a villain, he can be considered an anti-hero.
Despite having a frequent rivalry with Tom, bulldogs are generally a dog breed that is good with cats in real life.