In life we will all have to interact with people we don't necessarily like, it's a fact. So instead of avoiding it I'm going to try and help you deal with these people.
First off there are multiple categories into which these people fit. We have the ones we don't like but we can't be mean cause we need them, like your boss or a teacher. We will also meet the person that is just in your life that you don't like, it could be a friend of a friend or a colleague or whatever but point blank, you don't like them. Then finally, the little cousin you have to play with because your mom would kill you for being mean to, or the intern you can't be mean to without looking like an asshole to the office.
The superior
This is the person you dont like or can't stand but you can't be mean towards b cause they could fire you or make your life hell so some tricks I advise would be...
Bring their attention to something or someone else
This way you're not being mean to them but you're getting them off your back. Be sure if you're making them talk to someone else that the person won't kill you afterward.
You could also make up an excuse as to why you need to walk away quickly.
This is a classic. Say you have to make copies, you're going to tutoring if you're a student, or anything else that makes sense for you to walk away urgently.
The person you just can't stand
To deal with this person it really depends on your personality. If you're shy or confrontational the responses will differ.
For the shy
Drop subtle hints that show you don't want to be in their company. Excuse yourself from a conversation or don't engage them in a conversation.
For the confrontational
I am for one am in this category when it comes to dealing with people. If you are comfortable and really don't like the person (maybe even hate them) make it obvious you don't like them. Purposefully disagree with them on everything short of terrorism. Make snarky remarks not so subtly. And what I've found most effective is treating them like a child. While their talking just look them dead in the eye and wait for them to finish then pause, roll your eyes and say "that great sweetie" then immediately change the subject. Warning: this may cause a cat fight.
The child
That intern or little cousin you have that you have to be courteous too because you don't want to seem like an asshole. For these people I would recommend just giving them something to do. Make them get coffee or play with Lego, then run away and hide in a corner until they go away. (That's how I survive family reunions)
Overall, I hope I helped you guys out by showing you ways to deal with people you don't necessarily like.