One who has a sadistic personality disorder which is characterized by deriving satisfaction from the physical or psychological suffering of another person. A person of this type is controlling, likes to humiliate a person in public, disciplines brutally when in a position of power, and likes to intimidate people.
Sadist people are like;
SMBD people that like and participate inflicting pain.
"My friend seems to always put me down and it seems like he likes it."
"G" always seems to beat "Boo" for the smallest things."