The same as sadist. Someone who enjoys cruelty or pain unto him or herself.
Damn bro! Your girlfriend broke up with you 3 times and you're going back for more! You're such a sadic!
A sadist is one who enjoys inflicting pain on OTHERS. The description given by the other poster describes a masochist (someone who enjoys being inflicted with pain). I'd also like to point out that "sadic" is another way of saying "sadistic", not "sadist".
Pyramidhead is a sadic monster who attacks those who feel guilt or desire punishment (also known as a masochist).