Nithael was one of angels stationed on Earth after the Darkness' rising.
At some point, he tracked Lucifer's presence at a park, only to find he was inside Castiel's body. When he tried to kill him with an angel blade, Lucifer tells him to stop, and claims he's come to save the world from the Darkness as he is the only hope left to beat her. He also commented why Nithael also wants to take a job that makes he leave the original post, making his original task abandoned. However, Nithael doesn't believe him and tries to kill Lucifer again, saying if the Darkness is invincible it cannot be destroyed. Nithael's actions make Lucifer molecularly combust him, killing him.
- Nithael is angel of rejuvenation and eternal youth. In lore, the angel helps people to attain the mercy of God and longevity. He protects the heads of state, presidents, monarchs, princes and all the people who devote their lives to spirituality and charity. He favours the continuation and legitimacy of families and business stability. He also helps people who need help from individuals in high places and provides a quiet and safe existence.
- Nithael name means "God, the king of heaven". It also ironic, as he (in Supernatural-verse) was an lesser angel.