The "Arrowverse" is a shared universe of television series based on characters from DC Comics. It began with the show Arrow, which premiered in 2012, and has since expanded to include popular series like The Flash, Supergirl, and Legends of Tomorrow. These shows often feature crossover events, where characters from different series come together to face common threats. The Arrowverse is known for its interconnected storylines and character development, allowing fans to see their favorite heroes and villains interact in various ways. The universe is primarily produced by Greg Berlanti and has gained a dedicated fanbase for its engaging narratives and diverse representation of characters.