Utuboros (ウツボロス,Utsuborosu?) is the giant sea-serpent mini-boss in Launch Octopus' stage in Mega Man X and Mega Man Xtreme 2. It comes in and out of the sand, swimming through the room. The player can stand on the middle sections, though the head and tail will cause damage if touched. Destroying either the head or tail section will destroy the mechaniloid. If timed correctly, X can destroy Utuboros with a single Storm Tornado. There is also a hidden Utuboros inside a passage that only opens when the Cruiziler is destroyed, leading to a Heart Tank in Mega Man X, and a Body Upgrade in Mega Man Xtreme 2.
This enemy also makes a cameo appearance in the intro cartoon of the PlayStation remake of Mega Man X3, where X uses it to defeat Launch Octopus.
Scrap (スクラップ,Scrap?) is a broken Utuboros head that appears in the conveyor belts of Flame Mammoth's stage in Mega Man X and Mega Man Xtreme 2. They are harmless unless they fall on top of X.
"Utsubo" (ウツボ) is Japanese for moray eel. The name Utuboros could also be a reference to the word Uroboros which is the name of a serpent devouring its own tail, or a combination of the two. Ouroboros is also the name of the last stage in Mega Man ZX Advent, which is an air fortress shaped like its namesake.
In Mega Man ZX Advent, a broken Utuboros appears in the Oil Field area in one of the side-quests. If the quest is completed, it is put on display in one of the rooms from Hunter's Camp.