Malachy may refer to:
- Malachy (given name)
- Saint Malachy (1094–1148), Irish saint
- Malachy I (died 862), High King of Ireland
- Malachy II (948-1022), High King of Ireland
- GCH Palacegarden Malachy, winner of the 2012 Westminster Kennel Club Dog Show
Malachi may refer to:
- Malachi, Jewish prophet
- Book of Malachi, a book of the Hebrew Bible
- Malachi Cush (born 1980), Northern Irish singer/songwriter
- Malachi Martin (1921-1999), Catholic priest, writer and commentator
- Malachi Ritscher (1954–2006), activist and musician known for self-immolation
- The Malachi Brothers, fictional characters and the main antagonists in Happy Days
Malachai may refer to:
- Malachai, an album by The Legendary Pink Dots
- Malachai (band)