Antonio Radić, better known as agadmator, is a Croatian YouTuber and chess player. He has one of the most popular chess channels on YouTube, and was the most subscribed chess YouTuber from 2018 to late 2021, when he became the first chess content creator to cross the million-subscriber mark. He was eventually surpassed by GothamChess. Although he does not participate in many international chess tournaments, he is active on various online chess platforms, including Lichess and Chess.com. On his channel, Radić reviews recent tournament games from top players, historical matches, and chess compositions. He occasionally features his own real-time rapid games, played on Lichess.