Castlemaine may mean:
- Castlemaine, Victoria, a town in Victoria, Australia
- Castlemaine Football Club, an Australian rules football club
- Castlemaine railway station
- Castlemaine, County Kerry, a town in Ireland
- Castlemaine Perkins, a Queensland-based brewery, known for the XXXX range of beers
- Baron Castlemaine, in the peerage of Ireland
- Roger Palmer, 1st Earl of Castlemaine
- Barbara Palmer, 1st Duchess of Cleveland, wife of Roger Palmer
- HMAS Castlemaine, a ship in the Royal Australian Navy