nameless, unidentified, unknown, unnamed -- (being or having an unknown or unnamed source; "a poem by an unknown author"; "corporations responsible to nameless owners"; "an unnamed donor")
unknown -- (not known to exist; "things obscurely felt surged up from unknown depths")
obscure, unknown, unsung -- (not famous or acclaimed; "an obscure family"; "unsung heroes of the war")
strange, unknown -- (not known before; "used many strange words"; "saw many strange faces in the crowd"; "don't let anyone unknown into the house")