Klopfenstein is a surname. Notable people with the surname include:
Amélie Klopfenstein (born 2002), Swiss alpine skier Delphine Klopfenstein Broggini (born 1976), Swiss politician Joe Klopfenstein (born 1983), American football player Rachel Klopfenstein (born 1995), Mauritian athlete Roy Klopfenstein (born 1960), politician in Ohio, US Scott Klopfenstein (born 1977), American singer and multi-instrument musician Willy Klopfenstein (1921–2002), Swiss ski jumper