loner
noun
[ ˈləʊnə ]
• a person that prefers not to associate with others.
• "my interest in birdwatching had made me a bit of a loner"
Similar:
recluse,
introvert,
lone wolf,
hermit,
solitary,
misanthrope,
outsider,
maverick,
nonconformist,
individual,
hikikomori,
eremite,
cenobite,
anchorite,
stylite,
solitudinarian,