Synonyms for Loner:

n.

mouse, homebody, introvert, shrinking violet, wallflower. independent (noun)
hermit, recluse, misanthrope.
introvert (noun)
wallflower.
loner (noun)
lone wolf, lone hand.
lone wolf (noun)
lone hand.
recluse (noun)
hermit, lone wolf, introvert.

Other synonyms:

homebody, shrinking violet, recluse. hermit. mouse. misanthropist
misanthrope.
shy person
introvert.
Other relevant words:
hermit, homebody, misanthrope, introvert, mouse, recluse.