Ego the Living Planet

Ego the Living Planet is a unique space-faring life-form from Marvel comics, most often seen as a villain he is a dangerous and powerful alien who often wars with both humanoid races and other cosmic entities, he has also shown the ability to reproduce : forming such oddities as Id the Selfish Moon and Alter-Ego.

History
Egos was once Egros, a alien scientist from the Black Galaxy, whose home system was threated by a mysterious  possibly Gigantian entity known as The Stranger, who made the system's star go nova. Egros worked to create bunkers for his species to survive, but the star exploded sooner than expected, and Egros was killed by the blast, along with the rest of his species. However, The Stranger fused Egros' spirit with the planet and all life that once inhabited it, making Egros into a living planet, now known as Ego.

Abilities
Ego is in complete control of his body, which is completely alien in design - despite being a "living planet" Ego is constantly described as a vast biological life-form and has displayed an array of devastating abilities far beyond the measure of most humanoid life - he can form faces or other structures from his mass, he can devour entire colonies who try to land on his surface and is shown to have a gigantic brain with untold telepathic power comparable to entities such as Galactus.

As a "living planet" Ego is effectively immortal, having lived for centuries and being able to regenerate on a molecular level - with such age comes incredible knowledge and cunning, sufficient that he joined the Elders of the Universe during their attempts to usurp Galactus and effectively become gods in a new universe.

Ego is also capable of reproducing, when parts of his structure are broken off they may develop unique intelligence - such as happened in the creation of Alter-Ego.

Finally, Ego is able to move freely in space but this is not a natural trait and rather the result of a powerful engine that has grown within his structure - allowing the planet-sized being to travel the stars.