Muireadhach I (also written as Murethach, Murdoch or Maurice) is the second known Mormaer of Menteith.
He succeeded his father Gille Críst by the time of his appearance in a charter of William the Lion confirming the church at Moulin to Dunfermline Abbey.
He appears again in a charter agreement between Gilbert, Prior of St Andrews, and the local Céli Dé dating sometime after 1198.
The case apparently went to arbitration, and the king decided on the right of Muireadhch Óg.
On 13 December 1213, Muireadhach Mór resigned the Mormaerdom, taking lesser lands and titles in compensation.