Mechanical engineering

Mechanics in physics and applied mathematics, or one of its subdisciplines.

Card mechanic, a card cheat who specializes in sleight-of-hand manipulation of cards

Auto mechanic, a person who repairs automobiles.

Aircraft Maintenance Technician, or aircraft mechanic, a person who repairs aircraft.

Mechanic (Transformers), a character in Marvel Comics's Transformers

The Mechanic, a 1972 film starring Charles Bronson as a mob assassin

Mechanic, a person who uses tools to fix and maintain machinery

An assassin or hit man