Seamus Ó hÉilidhe (anglicised James O'Hely,[1] Latinised Jacobus Helius;[2] died c. March 1594) was an Irish clergyman and Roman Catholic Archbishop of Tuam.

He is known for his role in acquiring Spanish forces to assist the Irish in the Nine Years' War, though his mission was unsuccessful and he ultimately drowned in a shipwreck off Biscay.

[8] He met with councillor Don Juan de Idiáquez, the royal secretary,[6] who supervised King Philip II's dealings in the British Isles.

[5][1] At the Escorial, Ó hÉilidhe presented the Council of War "with a complete account of the warlike potential and strategic possibilities of the confederate Irish".

"[5] Idiáquez arranged for a ship to take Ó hÉilidhe, Spanish experts and Irish émigrés back to Ireland to gather intelligence and assist in the rebellion.

[10] The ship with Ó hÉilidhe set sail in March 1594, probably from Ferrol,[7] but was shipwrecked in a sandbar off the coast of Santander, Cantabria, which halted any further lobbying.

Indeed, on this date Hugh O'Neill and O'Donnell wrote to the King of Spain referencing the failure of Ó hÉilidhe's mission: "By the timidity or negligence of the messengers our former letters have not reached you".