Known as Diarmuid Ua Duibhne, Diarmid O'Dyna, and "Diarmuid of the Love Spot", he is from the Fenian Cycle in Irish Mythology. He is famous as the lover of Granne who was the intended wife of his lord Fionn. His foster father Aengus would give him his sword Moralltach, the Great Fury and Beagalltach, the Little Fury. Diarmuid is also said to have wielded two spears. Which are the smaller yellow Gáe Buide and the greater red Gáe Derg. Both spears were said to inflict wounds from which none could recover.
He slept with the female embodiment of youth who gave him a cursed lovespot on his forehead. Which would cause all women who look at it to fall in love with him. This would lead to Granne using a geis to bind him to leave with her and marry when they would have several children together. After his foster father convinced Fionn to pardon him the two would go on a boar hunt years later. Where a boar would heavily injure him and lead to his death when Fionn intentionally allowed the water that would heal Diarmuid's wounds fall from his hands before he brought it to him.