interloper
From Longman Dictionary of Contemporary Englishinterloperin‧ter‧lop‧er /ˈɪntələʊpə $ -tərloʊpər/ noun [countable] OUT/OUTSIDEsomeone who enters a place or group where they should not beExamples from the Corpusinterloper• They were treated as interlopers in their new country.Origin interloper (1500-1600) inter- + -loper (perhaps from Old English hleapan “to jump” or Middle Dutch lopen “to run”)