Buffy the Vampire Slayer's Buffy Summers was born on Jan. 19, 1980. "I just realized that today is Buffy Summers 40 bday," Gellar, who is four years older than her character, wrote on Instagram. "I can’t even believe that. She taught that the the hardest thing in the world is to live in it. So in her honor let’s all be brave. Live. This may not be the way we are used to living our lives, but let’s find the beauty. So we can all live long and safely."