Valach (feminine Valachová) is a Czech and Slovak surname, meaning Vlach. Notable people with the surname include:
Ján Valach (born 1973), Slovak road cyclist Juraj Valach (born 1973), Slovak ice hockey player Kateřina Valachová (born 1976), Czech politician Lucia Valachová (born 1997), Slovak cyclist Pavel Valach (born 1953), Czech volleyball player Radovan Valach (1910–2000), Slovak-Austrian freestyle wrestler Vladimír Valach (1937–2006), Slovak diplomat and economist