Scarab Fighter is Kang the Conqueror's multi-purpose combat robot. They can shift from air fighter to assault walker. They're launched from the Scarab motherships in flight.
They were equipped with advanced weapons systems and sturdy alloys. They have the self-repair mode when they're heavily damaged.
They first appeared in "Come the Conquerer" when Kang launched his invasion of the 21st century Earth with Scarab fighters. All militaries and other heroes in the world including S.H.I.E.L.D. and the Avengers tried to stop them but were nearly overwhelmed due to huge numbers of them being launched by the Scarab motherships.
They were defeated when the Avengers infiltrated Damocles to end this invasion once and for all. After the invasion, their remains some intact were taken by S.H.I.E.L.D for studying and research.