The heel is the villain and are the "bad guys" in pro wrestling. Some "tweeners" who aren't classified as good or bad can exhibit heel characteristics.
No matter the kind of heel, their job is to be the antagonist. Heels exist to foil the babyface wrestlers.
Sometimes If a heel is cheered over the "good guy," a promoter may turn that heel to a face or make the wrestler do something even more despicable to garner more heel heat.
As for me, I always cheer for the heel because a great heel will make a face even bigger.
Now let's take a look at the top five heels over the last two decades.
1. "HBK" Shawn Michaels
3. Chris Jericho
4. Ric Flair
6. Bret Hart
7. The Undertaker (Classic, Ministry of Darkness and Red Devil)
8. Kevin Nash
9. Scott Hall
11. "The Million Dollar Man" Ted DiBiase
12. Mankind (Classic)
13. Kane (Masked)
15. Kurt Angle
16. Jeff Jarrett
17. Brock Lesnar
18. Eddie Guerrero
19. Brian Pillman
21. Curt Hennig
22. Shane Douglas
23. Paul Wight (The Giant and The Big Show)
24. Owen Hart