Gormlaith nic Conaing (born 1 January 849) was the wife of Count Guihomarch of Leon during the late 9th century. On 19 August 872, Gormlaith and her children Tedvil verch Guihomarch and Iudprost verch Guihomarch were captured by the Viking warlord Hastein following his capture of her husband's capital of Kastell-Paol, and Gormlaith was forced to become one of Hastein's concubines to shame her husband. On 25 December 876, she gave birth to a daughter, Halla Haesteinnsdottir. On 13 July 880, she was discovered to have backed Cristen's plot to assassinate Hastein, and Hastein had Cristen and fellow plotter Rivod mab Gestin executed, while Gormlaith fled to Ivrea before she could be imprisoned.