Cathal O'Connor Faly

Cathal O'Connor Faly (Irish: Cathal Ó Conchobhair Failghe; c. 1540 – October 1596) was an Irish rebel of noble ancestry.

As a young man, O'Connor Faly was a political spy for Catholics in Great Britain. He became a rebel and killed English soldier Henry Mackworth before escaping to Spain in the 1580s, where he joined the Spanish Armada. Known by the Spanish as Don Carlos, he died in a shipwreck on the 2nd Armada.

His claim to the lordship of Offaly (Irish: Uí Failghe) was recognised by the Spanish, but not by the English.