intruder
noun
[ ɪnˈtruːdə ]
• a person who intrudes, especially into a building with criminal intent.
• "the intruder had pulled out drawers and dumped their contents on the floor"
Similar:
trespasser,
interloper,
invader,
prowler,
infiltrator,
encroacher,
violator,
burglar,
housebreaker,
thief,
raider,
robber,
cat burglar,