Time: Early 2000's or maybe earlier
Genre: Sci-fi/Comedy/Dark
Narrative work: A novelette or a story book
Language: Might be in another language than English. Possibly French
Plot: There is a hungry, funny looking alien from another dimension who keeps eating things and gaining power. The more power he gains, the bigger things he can eat. I think when he poops, he creates something else based on what he eats.
He arrives at Earth or Earth-like planet at some point and he is weak. He starts eating smaller things like stones and pickles, then other living things, then mountains, then planets, then galaxies and he becomes so powerful that he eats the whole universe. He finds himself in vast emptiness. After some contemplation and silence, his stomach starts growling and making strange noises. He closes his eyes and holds his stomach. Suddenly, he poops with force and ejects multiple universes. After some time, all universes decide to ally and fight against him.
I think he had a weakness to some kind of material from his dimension and there was another creature from his dimension helping to defeat him.