Bélchú

Bélchú (also known as Bealchu or Bealcu) of Breifne is a warrior of Connacht in the Ulster Cycle of Irish Mythology.

When he found the Ulster hero Conall Cernach near to death after his final combat with Cet mac Mágach he took him home and tended to his wounds, intending to fight him when Conall was fit enough. As Conall recuperated Bélchú regretted this honourable behaviour and told his three sons to kill Conall as he slept in his sickbed. Conall overheard and made Bélchú take his place in the bed, so when the sons arrived, they killed their father instead. Conall then killed all three of them, and took all four heads home.

Reference

Meyer, Kuno. The Death-Tales of the Ulster Heroes