Would you tell me about four of the ten smartest people you've ever known?

Never mind figuring out if they’re the four smartest. How would you know that, anyway? Just as long as they’re up there near the top. How would you describe them?

For instance:
How do you know them?
What sort of people are (or were) they?
What are their personalities like, and what do they do?
How much do you think their braininess defines them?
Would you call them successful by ordinary standards?
Do you like them?
Have you ever envied them? or pitied them?