Charles Augustus Magnussen is a fictional character from the Sherlock Holmes universe, created by Arthur Conan Doyle. He is portrayed as a highly intelligent and manipulative criminal mastermind, often referred to as a "consulting criminal." Magnussen is known for his ability to gather and exploit sensitive information, making him a formidable adversary for Sherlock Holmes and John Watson. In the BBC adaptation of Sherlock, Magnussen is played by actor Lars Mikkelsen. His character is introduced in the third season and serves as the primary antagonist. Magnussen's cunning nature and psychological tactics challenge Holmes, showcasing the detective's intellectual prowess in a battle of wits.