|Irish name||Cathal Ó Mainnín|
|Position||Right Corner Forward|
22 October 1994|
|Height||1.85 m (6 ft 1 in)|
Born in Ahascragh, County Galway, Mannion first excelled at hurling during his schooling at St. Cuan's College. He arrived on the inter-county scene at the age of sixteen when he first linked up with the Galway minor team before later joining the under-21 side. He made his senior debut during the 2014 league. Mannion immediately became a regular member of the starting fifteen.
Mannion has been a member of the Connacht inter-provincial team on several occasions. At club level he plays with Ahascragh-Fohenagh.
- GAA GPA All Stars Awards (1): 2015
- "Cathal Mannion: Galway can hit heights once more". RTE Sport. 30 May 2015. Retrieved 8 June 2015.