Fantastic Four (1961) 235-A

"Four Against Ego!"

As the FF crash land on the living planet, they discover that the planet is propelled by a giant engine. They head off to investigate the engine and Reed figures out a way to use its power cell to stop the living planet. The FF head down into the living planet with the power cell, planning to detonate it on the brain of the planet. The heat and pressure of the descent is too much for all of the team save for Ben. Ben reaches the core of the planet where he learns that the mad planet had been visited by both Galactus and Thor and that it was that team that banished Ego into deep space. Ben throws the power cell at the brain but misses. All would be lost, but when Ego fires the engines only one works. This throws the living planet off course and into the sun. As Ego melts, the FF recover Ben, adrift in space, and return home.

The Fantastic Four battle Ego the Living Planet.