Olympian, above all that, aloof, backward, bashful, blank, chilled, chilly, cold, constrained, cool, detached, discreet, distant, eremitic, exclusive, expressionless, forbidding, frigid, frosty, guarded, haughty, highfalutin, icy, impassive, impersonal, inaccessible, insociable, introverted, lordly, misanthropic, modest, offish, pompous, reclusive, remote, removed, repressed, reserved, restrained, reticent, retiring, seclusive, shrinking, snooty, solitary, standoff, subdued, suppressed, unaffable, unapproachable, uncompanionable, uncongenial, undemonstrative, unexpansive, unfriendly, ungenial, unsociable, unsocial, withdrawn

For further exploring for "standoffish" in Webster Dictionary Online