Donnacha is an Irish given name; a variant of Donnchadh. Notable people with the name include:
Donnacha Cody (born 1985), Irish hurler for the Kilkenny senior team Donnacha Dennehy (born 1970), Irish composer Donnacha Fahy (born 1979), Irish hurler for Tipperary GAA Donnacha O'Brien (born 1998), Irish jockey Donnacha O'Dea (born 1948), Irish professional poker player and swimmer Donnacha Ryan (born 1983), Irish rugby union player