Some may think unicorns are the rarest creatures in all of Ark. Not really. According to the internet, Phoenix was the rarest creature. The YouTuber Schwalbe, said the rarest creature, was Noctis. If you do not know, Noctis is basically a fire-like unicorn. It's certainly bigger than the Unicorn, and is more of a boss, because it has a rare chance to spawn once you go through the boss teleporter in Dungeons. You'd simply have to tame it, to beat the Dungeon. It would be tamed with Rockarrots. Noctis and the Phoenix do indeed rival eachother, because if I am not mistaken, the Phoenix only spawns during a heatwave. But Noctis, according to Schwalbe, has etheir a 1 in a 100 chance to spawn instead of a boss when you go through the boss teleporter. If not 100, 1000. I'd say Noctis would be the rarest, since it has a 1 in 100 or 1 in a 1000 chance of spawning instead of a boss. Though, heatwaves are not too common. Since you'd have to wait for an actual heatwave to occur. Though some may disagree, because Noctis is probably more considered as a boss in Ark. But bosses, can be considered creatures too. Perhaps it is Phoenix, or maybe Noctis. If you look it up, it will indeed say Phoenix is the rarest, but maybe you should look up Noctis too.