Lon Chaney Sr. was an iconic American actor known for his remarkable ability to transform into various characters, particularly in the silent film era during the 1920s. His dedication to his craft and use of elaborate makeup techniques set a new standard for character acting, influencing the horror genre significantly. Chaney’s roles in films like 'The Phantom of the Opera' and 'The Hunchback of Notre Dame' made him a legendary figure, capturing audiences with his powerful performances that transcended the limitations of silent cinema.