Prof. William Boyd is a supporting character in the anime Make My Day who appears in the latter part of the story, from episode five onward. He is a scientist presented as the leading authority on the Swarm, the mysterious creatures that emerge from beneath the frozen surface of a remote colony planet and begin attacking its inhabitants. Because of his expertise, Boyd is closely connected to the scientific effort to understand the threat, and he works alongside his assistant, Rachel Wise, who accompanies him through the main events of his role.

During the crisis, Boyd and Rachel are held in a military prison, a situation that places the colony's key researchers under military control while the settlement descends into chaos. His function in the narrative is therefore tied to his knowledge rather than to direct combat, with his partnership with Rachel Wise serving as the main personal connection shown for him. As the series reaches its conclusion, Boyd is among the survivors who look toward the future with hope, closing his part of the story on a note of cautious optimism after the ordeal.