A question on character and permission

If you create a character "based" on a person, a real live person, do you need to have their permission? Meaning, should you contact them and say "While this person is not you, I have used some of your life to base this character on."

Or

Do I give an acknowledgement and give credit to what I wrote?

good grief, no! You change the person's characteristics enough so no one recognizes himself (the bald 60 yo uncle who works in a factory and collects stamps becomes a graying 40 yo teacher who's a NASCAR freak) and keep your mouth shut!!

Tell yourself: It's a FICTIONAL CHARACTER. Any resemblance to actual person or events are entirely coincidental.

Now breathe.

Be very careful if you use a real person as a character in your book! It can get you sued out the wazzoo.

I'd recommend against this.

What's so special about this real person (presumably a celebrity) that makes you want to put them into your book? Why not excerpt a few characteristics of that person, blend with fictional things, and create a totally new character?

It's a lot safer.

(the term "wazzoo" is a highly technical phrase)

I use real characters , complete with names and descriptions, in my novels on a regular basis, and never have asked permission, but the protagonist is always fictional. But most characters are based on real people in one way or another.
Just change the name and a bit of description, and forget about it.

I only do it with dead people (Eww. That came out wrong.) The dead can't sue you for libel.