Robo-X (or just Robot X) is the fifth boss of Streets of Rage 3.
After beating some of Mr. X's minions, Mr. X will appear to spontaneously combust before revealing his true identityr. Robo-X slides around the arena, stopping to fire a machine gun on his hand or launch a homing missile. If the player gets within melee range he will throw a quick series of consecutive punches. If a player grabs him and hesitates before throwing, after a moment he'll electrify himself, doing the player some damager. After attacking the player, he'll stop to laugh, giving the player a chance to attack him.
After his defeat, in Easy mode in the English version of this game, he'll tell the player to play Normal or Hard mode. If the player does defeat him in Normal or Hard mode, the player will have access to Stage 6. On the Japanese version the player can access the 6th stage regardless of difficulty.