eponym (n.)

one whose name becomes that of a place, a people, an era, an institution, etc., 1833, from Greek eponymos "given as a name, giving one's name to something," as a plural noun (short for eponymoi heroes) denoting founders (legendary or real) of tribes, cities, etc.; from combining form of epi "upon, (called) after," (see epi-) + onyma, Aeolic dialectal variant of onoma "name" (see name (n.)).