Do the Avengers defeat Thanos?

As an expert in the Marvel Cinematic Universe (MCU), I have closely followed the storylines and character developments that lead to the climactic battles involving Thanos. The question of whether the Avengers defeat Thanos is one that encompasses multiple films and storylines within the MCU.

In "Avengers: Infinity War," Thanos successfully collects all six Infinity Stones and achieves his goal, leading to a significant loss for the Avengers. However, the story continues in "Avengers: Endgame," where the surviving Avengers, along with some new allies, devise a plan to reverse the effects of Thanos' actions.

In "Avengers: Endgame," the Avengers do indeed defeat Thanos in two significant battles. The first battle occurs in the past during the time-heist operation, where the Avengers manage to collect the Infinity Stones before Thanos can. The second battle takes place in the main timeline when Thanos from the past is brought to the present and is defeated by the Avengers and their allies in a massive, final showdown.

So, to answer your question, yes, the Avengers defeat Thanos, but the journey to that victory is complex and involves time travel, sacrifice, and the efforts of numerous characters across the MCU.

Warlock had learned of Thanos' activity and recruited Captain Marvel and the Avengers to again oppose the mad Titan. Captain Marvel managed to destroy the synthetic Soul Gem, but Thanos captured the Avengers and even killed Adam Warlock after an intense one-on-one battle. ... Thanos again defeated them all.