Marco Diaz is a fictional character from the animated television series Star vs. the Forces of Evil. He is a teenage boy who is best friends with the main character, Star Butterfly. Marco is known for his kind-hearted nature, bravery, and strong sense of loyalty. In the series, Marco often finds himself in various adventures alongside Star as they battle magical creatures and navigate the challenges of growing up. He is also a skilled martial artist, which helps him in their quests. Marco's character development throughout the show highlights themes of friendship and self-discovery.