For the Twilight Zone fans, there is an episode (Queen of the Nile) where an immortal Egyptian princess is alive, in the modern day. She lives off of male souls to continue her immortality. She mentions to one of her victims that she's 38. If she's immortal, why choose 38 to live forever? She explains she chose it because any younger, and others consider you too inexperienced to take seriously; any older and you lose attractiveness/health. Perfect age? Maybe. Granted, this is a tv show from 1964. Food for thought.