20GILES SURVIVED DARK WILLOW
After an enduring battle, a magically imbued Giles dosed Willow with emotionally overwhelming magics. She goes to end the world and Giles, beaten down and lying on the floor, tells Anya he’s dying. Looking confused, and presumably able to sense the end with her demon powers, Anya tells him he
However, when she teleports to Buffy and Dawn in the cave, she’s worried about Giles, noting he doesn’t have much time. Then, after Xander talks Willow down, Giles sits up and Anya is surprised he's alive. You could argue he never perished or somehow Willow’s defeat resurrected him. Either Way, it was never explained and had little dramatic affect since even the characters couldn’t agree on whether he was dying or not.