One who is involved with all Technical aspects of a show/film/production, including but not limited to: Lighting Design/programming/implementation; Set Design/Construction; Prop Design/Construction; Costume design/construction; etcetra
Commonly known to wear all black, Join IATSE, and generally to have rather sick senses of humor. (Warning to all actors, they have Gaffers tape, they will stick you to the wall)
Note: The Stage/Production Manager can be considered to be a Techie, for they are considered "god" on set, the reason I set this aside is because they are not involved with IATSE, but with Equity.
the lighting designer Is a Techie.
the actors are most definitely not.