Who defeated thanos in marvel comics?

The supplied sources discuss Eternity, a cosmic entity, and do not mention Thanos or any confrontation involving him. Therefore, no information in the verified evidence indicates a specific character or event that defeated Thanos. In Marvel comics, Thanos has faced many opponents, but the details of a defeat are not part of the given data. Without additional evidence, it is not possible to answer who defeated Thanos. Consequently, any claim would be speculative and is not supported by the verified sources.