Yu-Gi-Oh! GX episode 132: "A New World Order"
Harpie's Brother, known as Birdman in the Japanese version, is a winged warrior who guards the power generator in the second alternate dimension that Jaden Yuki and his companions visit. He possesses the world view that high-level monsters are superior to those of lower level, and have the right to abuse them. After suffering a defeat to Jaden, he ultimately dies (in the English version, his energy is sent to the stars), but not after regretting his past actions and asking Jaden to save his world.
Harpie's Brother is seen one more time prior to Jaden's Duel with Yubel, as Jaden remembers all the people Yubel has wronged.