Y100 or Y-100 may refer to: Yttrium-100 (Y-100 or 100Y), an isotope of yttrium
Radio stations branded "Y100" KCYY in San Antonio, Texas WHYI in Miami, Florida WNCY in Green Bay, Wisconsin WPLY, former station in Philadelphia, Pennsylvania WSGY, former station in Tifton, Georgia WXYY, former station in Rincon, Georgia WZJZ in Ft. Myers, Florida