The Mugger is an alien of unknown species that is seen in Ulence Flats. He is the version from the Space Quest I: Roger Wilco in the Sarien Encounter (time sector) who replaced the Mugger (original version).
His angle is to hit up recent winners of Buckazoids from the slot machine in the Rocket Bar, luring them behind the bar with the offer of a mode of transportation for sale, but then proceeds to stick them up and relieve them of their Buckazoids, though he will leave a handful of Buckazoids for the especially hard up, like Roger Wilco. If the mark doesn't pay up, or doesn't leave straight back the way they came, he has no qualms about shooting them. He's also been known to loot the bodies of any poor souls that end up getting overly drunk on Keronian Ale, even going so far as stripping bodies for parts.
Soon after a timepod presumably carrying a time traveling Roger Wilco appeared next to the mugger... One can only assume how the encounter ensued (see Parallel universes).