From Liquipedia StarCraft Brood War Wiki

Mechanical units are fully or partially composed of non-living matter.

Terran - SCV, Vulture, Goliath, Siege Tank, Wraith, Science Vessel, Dropship, Valkyrie and Battlecruiser.
Protoss - Probe, Dragoon, Reaver, Scout, Observer, Shuttle, Corsair, Arbiter, Carrier, and Interceptor.

Also refers to Terran factory units in a game. "The Terran is doing a 'mechanized' build vs this Zerg"


  • Terran mechanical units can be repaired by one or more SCVs.
  • Lockdown can target only these units.
  • The SCV is also a biological unit.