How did Galactus threaten entire planets?

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Heath Ledger as the Joker sits at an interrogation table with Christian Bale as Batman standing behind him in a scene from the film The Dark Knight. — Supervillain Heath Ledger (seated) as the Joker and Christian Bale as Batman in *The Dark Knight* (2008).

Galactus is a colossal, skyscraper-sized alien who threatens entire planets by consuming their life force. As a powerful cosmic entity, he sustains himself through this destructive process, which serves as his primary method of posing a threat to civilizations throughout the universe.1

In his appearances, Galactus often employs a herald to scout for suitable worlds to consume. One of his most notable heralds was Norrin Radd, who became the Silver Surfer after Galactus agreed to spare his home planet, Zenn-La, in exchange for his service.2