| Manus O'Donnell Maghnus Ó Domhnaill | |
| Birth Place: | Tyrconnell, Ireland |
| Death Date: | 22 October 1600 (aged ~21) |
| Death Place: | Lifford, Tyrconnell, Ireland |
| Burial Place: | Donegal Abbey |
| Father: | Hugh McManus O'Donnell |
| Mother: | Iníon Dubh |
Manus O'Donnell (; – 22 October 1600) was an Irish nobleman and member of the O'Donnell dynasty.
Manus was the third son of Hugh McManus O'Donnell, the Irish Gaelic Lord of Tyrconnell, and his second wife Iníon Dubh. Manus had two older brothers, Hugh Roe and Rory, and a younger brother Cathbarr. He also had several sisters – Nuala, Mary and Margaret.
Manus was killed by his loyalist cousin Niall Garve O'Donnell during the Battle of Lifford.[1] [2] He was buried in Donegal Abbey.