Alien Seer

The Alien Seer is an unnamed extraterrestrial seer who is responsible for giving Boros the prophecy about the worthy opponent he is desperate to face.

Appearance
In the manga and anime, the seer is an alien with 8 eyes and multiple tentacles on its face.

Alien Conquerors Arc
Boros mentions the seer's prophecy to Saitama about the worthy opponent on Earth while they are fighting. However, the seer never reveals the identity of the worthy opponent to Boros.

Supernatural Abilities
Clairvoyance: The seer was shown to have this ability, as it deducted the prophecy about the worthy opponent to Boros. However, it's never states the true identity of the opponent.