Well, it's complicated. The problem is that the line between acceptable and unacceptable is pretty blurry, and difficult to parse from a brief forum post.
Step One: Are you overreacting?
To begin with, a certain amount of mockery is pretty much standard practice. Calling inhuman characters the names of domesticated animals is extremely common (cow, kitty, pup, etc.), to the point where I'd expect a certain amount of it.
At best it's a term of endearment. At worst... Well, there are crueler barbs that can be passed around.
One thing that seems problematic is this quote:
You know that I won't start a PvP combat, but your character sees a Minotaur ready for combat and you insult him all the time.
This makes it sound like you expect the other players to be too scared of your character to joke with (or at) him. That's a big no-no. No matter how big, scary, monstrous, serious, or powerful your character is, the other players are your peers. Even if you think you can take them in a fight, the assumption is that all player-characters are equal on some level.
Step Two: Communication
If it's really bothering you, talk to the players about it. Ask them if they could try to tone things down a bit. Most likely they just think everyone is having a good time... Reasonable groups will check themselves (a bit) when asked.
Step Three: What else can you do?
So, what are some triggers for bad group behavior that you can avoid?
PCs or NPCs that are knockoffs of Drzzt, for example. Or even certain archetypes like the "brooding loner born of tragedy in his past." Players can recognize the one-dimensional nature of these characters ("really, you never laugh?"), and usually respond in kind.
Remember that the other players only see a very limited amount of the character's back story. Even if your history is unique and beautiful, if the outcome of that history is "brooding loner" that's all that matters.
A relative of the above point. If players expect a Star Wars - style adventure, but get something grim, dark, and gritty, they'll be more likely to pick at its flaws. Vice versa is true as well.
Playstyle mismatch could factor in as well -- If the group is expecting a hack-and-slash dungeon cawl, and gets an elaborate political game, they'll have difficulty engaging with it.
Remember that role playing is a collaborative process. If the game is spending too much time on one player trying to elaborate their backstory, or the DM trying to tell the history of the world, the players will begin to lose interest. When is it their turn to fill in?
Players that aren't engaged with the story (due to tone mismatch, lack of interactivity, or simply not being interested in the plot) are likely to amuse themselves in other ways.
There's a long tradition of using made up names in fantasy. If you do that, make sure your names are simple, and easy to pronounce out loud. Stick to phonemes within the other players' native languages.
Even if the other players aren't malicious, their brains will still simplify things to something they're familiar with. That usually won't be something flattering.
Lack of in-game consequences
Every once in a while, it's a good idea to call the players on their shenanigans within the game. Not every time... But every once in a while planting your feet and refusing to follow the plan until the players stop calling you a cow can help.
Be crafty in your reaction. Not every slight deserves a fight to the death. Pick your battles and your responses to be appropriate and effective.
It may be something they're looking for
Sometimes, it can be fun to just have the villain get really angry and frustrated at having the heroes continually butchering his name. Weave it into the plot, and have fun with it.
Step Four: Are they making fun of you directly, or just your characters?
This is the last point, because it's an uncomfortable topic. Sometimes a group of people will have someone that's singled out as a pariah. The butt of all jokes. The whipping boy.
If that's you, and talking it out doesn't help, then you need to start adding distance quickly.
Step Five: That last point was kind of dark, wasn't it? Let's not end there
Here's some comics that show utterly toxic DM/player relationships. See if you can spot where things went wrong:
DM of the Rings
Darths and Droids