Out of all the beloved comics from the past, the most beloved of them all could quite possibly be Calvin and Hobbes. Featuring the adventures of an imaginative 6-year-old boy and his stuffed tiger, the comic ran for 10 years from 1985 through 1995, yet it is still remembered quite fondly even today.
The strip itself had a limited number of characters featured in it, making their characterizations even better and more apparent. Of course, Calvin being the hyperactive free thinker that he is, he often sees just about everyone around him, both real and imaginary, as enemies of his trying to ruin his fun.
The Baseball
It's no secret that Calvin doesn't like baseball that much, which is why he changes the rules to his liking. But the sport also has spawned a deadly enemy in the form of a monster baseball.
When playing baseball, sometimes the ball sprouts teeth and tries to chomp on Calvin, leading him to take several measures to run away and defend himself. Unfortunately, not even Hobbes believes him when he tells him that the ball attacks him. Luckily for Calvin, the times in which the baseball turns into a monster are limited, making it usually safe for him to play the game in his own special way.
The Bike
Despite Calvin's Dad's best advice, Calvin still hasn't learned how to ride his bike, partly because most of the time, he sees it as a sentient being wanting to kill him.
There are multiple strips in which Calvin battles the bike, though nearly every attempt ends in disaster and leaves Calvin a mess. Even when Calvin wins against the bike, such as letting all the air out of the tires, his victories are short-lived thanks to his dad, who simply thinks that Calvin is struggling to learn how to ride the bike and simply believes that Calvin's dirty state whenever the bike attacks is the result of him falling off.
Moe
While many Calvin and Hobbes strips are heartwarming, others are far from it, especially when it comes to Calvin facing off against Moe, the class bully.
Moe is big, dumb, and really tough. His favorite thing to do is pick on Calvin, often beating him up even if he doesn't provoke him. No matter what Calvin tries, Moe still punches him down. Not even Mrs. Wormwood is able to keep Moe's bullying at bay despite Calvin's Mom telling her about what was going on. The only time Calvin really beats Moe is when he uses Hobbes and has Moe convinced that trying to attack Calvin or take the tiger is a trap.
Miss Wormwood
Miss Wormwood, Calvin's teacher, isn't all that bad. After all, she's really just trying to do her job and educate the kids in her class.
Unfortunately, Calvin has no desire to be educated, and will often disrupt class in various ways, leading to many conflicts between the teacher and her student. While Calvin does his best to mess up lectures in any way he can, his actions will often lead to Miss Wormwood disciplining him via a dunce cap or a swift trip to the principal's office. Still, she does get the benefit of the doubt, as she will often keep an open mind when Calvin asks a question, hoping that, for once, it's a serious question and not something completely off-topic.
Deranged Mutant Killer Monster Snow Goons
Calvin's snowmen are weird and creative, but mostly harmless. The Snow Goons, however, are easily some of Calvin's worst enemies.
The Snow Goons were accidentally created by Calvin after he brought a snowman to life, who then proceeded to mutate himself and build more mutated snowmen. Given that Calvin's only weapons at the time were snowballs, which would only make them stronger, the Snow Goons seemed unstoppable. Luckily, Calvin's quick thinking to use the hose in order to freeze them solid during the middle of the night led to their quick and easy demise.
Dad
Many times, when there are Calvin and Hobbes strips about parenting, it leads to Calvin's Dad giving some sort of lecture and punishment to Calvin for stuff he's done.
Dad is a strict man when it comes to discipline, and he's no stranger to punishing Calvin off panel for some of the chaotic things he's done. But he's also fair, and even he recognizes when the things that Calvin does turn out to be no more than accidents. While Calvin does go up against him due to ideological differences at times, it does seem like Dad is more accepting of Calvin and his actions, even though he has said multiple times that he wanted a dog rather than a kid.
Mom
Calvin's mom tends to freak out far more often than his dad, leading to Calvin coming into conflict with her far more than him.
Mom tends to be more strict than Dad, possibly because she's had to deal with Calvin's antics way more than he has due to him being at work most of the day. Because of this and her punishments for Calvin, he often pictures her as one of the recurring villains in his fantasies as Spaceman Spiff or Stupendous Man, which often leads to even more conflict and getting himself into even more trouble.
The Monsters Under The Bed
While readers don't really ever see the Monsters Under the Bed, their recurring appearance trying to lure Calvin out of his bed so they can eat him is both hilarious and disturbing.
Many times as Calvin tries to go to sleep, the Monsters try to tempt him into leaving the bed with various tricks, including trying to make him want to go to the bathroom, pretending to be his mother, and even trying to convince Hobbes to push him over the side. Their attempts always fall short thanks to Calvin's quick wits and knowing exactly what they're trying to do. Still, being hungry monsters, they still try their best to trick him so they can feast on his bones.
Rosalyn
More often than not, Calvin believes his babysitter, Rosalyn, to be a sadistic and evil simply because she sends him to bed way earlier than usual. Thus, he fights her with various tricks and pranks.
These pranks have a pretty wide range of intensity, from stealing her study notes and threatening to flush them down the toilet to locking her out of the house. However, these pranks from Calvin always lead to even more trouble from both Rosalyn and his parents. While by the end of the strip Rosalyn and Calvin seem to make peace through a game of Calvinball, it doesn't change the fact that Calvin hates and fears her throughout much of the strip's run.
Susie
By far, the person Calvin sees as his biggest and most hated enemy in life is Susie, the girl with whom he is often seen all throughout the strip.
Susie serves as a foil to Calvin. While he is emotional and easily upset, Susie is calm and cares about school. Because of her personality, Calvin goes after her in various ways, mostly with snowballs in winter or water balloons in summer. Despite the antipathy, it was hinted a few times that Calvin might actually have a crush on Susie, making all his actions to try to hurt her and make fun of her seem like cries for attention.