Thor is technically the first Avenger.

All about Thor

Thor is a superhero in the Marvel Universe. He is the Norse God of Thunder, and he has a magical hammer called Mjolnir, which only he can lift, and it helps him control lightning and the weather. Thor is strong, brave, and always fights for what is right. He is a member of the Avengers, a group of superheroes who protect the Earth from threats like aliens and supervillains. Thor is a great warrior and a skilled fighter. He is also very clever and has a good sense of humor. He has a big heart and cares deeply for the people he protects. Thor is also very proud and sometimes can be a little bit stubborn. He loves a good battle, but he always tries to find a peaceful solution to problems first.