McGregor

Father McGregor is a character mentioned in Fire Emblem: The Sacred Stones. In flashbacks, it is revealed that he was a high-ranking priest of Grado and apparently a tutor in history for Prince Lyon and Prince Ephraim and Princess Eirika during their time in Grado, and apparently lectured Ephraim a lot for not taking his dutie seriously.

When Lyon intended to use Grado's Sacred Stone for research, Father McGregor strongly opposed, and denied him direct access to the stone. However, after the death of Emperor Vigarde, his son Lyon finally gained access to it, and the shaman Knoll reveals that Lyon executed him personally for opposing him. It's hinted (though not confirmed) that he was the mentor of the clering Natasha with whom he managed to reveal the secret so she could warn the other nations of it before he was killed.