Murchadh Ó Madadhan (died 1327) was King of Síol Anmchadha.
Murchad of Magh Bealaigh, who was Chief from 1286 to 1327. Murchad married Marcella, daughter of Eoghan Ó Cellaigh. In 1327 He resigned his chieftainship of his own accord and went away from Royal Rule to Rome, to resign his soul to the Supreme King, and his body to the cemetery of Saint Peter in the chief city.
References
http://www.rootsweb.ancestry.com/~irlkik/ihm/uimaine.htm Annals of Ulster at CELT: Corpus of Electronic Texts at University College Cork Annals of Tigernach at CELT: Corpus of Electronic Texts at University College Cork Revised edition of McCarthy's synchronisms at Trinity College Dublin.
http://www.ucc.ie/celt/published/G105007/index.html