Phantoon is an alien ghost and a boss in the video games, Super Metroid and Metroid: Other M.
Phantoon is an alien ghost. His entire body looks like a grey alien's head and has green skin. He also has tenticles for arms, and an eye surrounded by teeth that is his weak spot.
Phantoon made his first appearance in Super Metroid. Samus fights him in a wrecked ship. Phantoon fights by teleporting at random areas and producing ghostly fire. Eventually, Phantoon's eye opens, giving Samus a chance to shoot at Phantoon. After Samus defeats Phantoon, Phantoon disappears and the wrecked ship's power is restored.
Other MPhantoon appears as the Bigger Bad and a super-boss in Metroid: Other M.
When Samus returns to the Bottle Ship to retrieve Adam's helmet, she comes across a bunch of strange creatures emerging out of dark pools. As she was heading towards the Control Room, Phantoon appears in front of her and seeks revenge after being defeated for the first time. Phantoon has definitely shown some significant changes. Phantoon is roughly twenty times bigger than before, is far more powerful, and has a bigger arsenal to fight Samus with. Phantoon summons ghostly hands to attack Samus, creates giant pools of darkness around the area, and he shoots homing ghostly fireballs practically non-stop. Phantoon's main weakness is his eye, and after Samus defeats Phantoon, he drifts into space and explodes.
It is possible that Phantoon was behind MB taking over the Bottle Ship, and assumes full control of it after her death, until Samus returns and destroys him.