Voltron: Defender of the Universe Season 1 Episode 51 Lotor's New Hit Man

An ambitious pilot with a deadly reputation as a loose cannon confronts King Zarkon, promising that he will destroy Voltron in exchange for a position of rank. The officers of Planet Doom are not happy, but Zarkon gives the ace pilot the fastest Robeast ever built. With a Robeast faster than Voltron, and a pilot more skilled than Keith and the Voltron Force is in a tough spot.