Morholt

A Irish knight and Knight of the Round Table. 
He comes to Cornwall to collect tribute owed to his country, before being challenged by Tristan. Tristan mortally wounds Morholt, leaving a piece of his sword in the Irishman's skull, but Morholt stabs him with a poisoned spear and escapes to Ireland to die. The injured Tristan eventually travels to Ireland incognito to receive healing from Iseult the Younger, but is found out when the queen discovers the piece of metal found in her brother's head fits perfectly into a chink in Tristan's blade.