Graduated from Tree's Academy of Dramatic Art.
Known for his vast portrayals of fictional and non-fictional fellows. Played Dr. Watson in Sherlock Holmes (1932), and then played the super-sleuth himself in A Study in Scarlet (1933), thus making him the only actor to play both roles. Also played King Louis XV in three different films.
Returned to Broadway in 1972, the year he died, in the Phil Silvers-led production of "A Funny Thing Happened on the Way to the Forum.".
Was in the process of writing his autobiography at the time of his death.
Was not originally scheduled to play Ebenezer Scrooge in the MGM classic version of A Christmas Carol (1938). Reginald was a last-minute replacement for the ailing Lionel Barrymore.