The villains of melodrama as well as those of Shakespeare provided some of the juiciest roles for an actor. Indeed, many of the great actors like Robert Mantell, John McCullough, and Thomas W. Keene made a specialty of Richard III. In lines of business, it was normally the heavy who got the villain roles, but the role of Richard III always went to the leading man instead of the heavy. Similarly, Othello's malignant antagonist Iago was considered by many to be Edwin Booth's best role.
William A. Brady's recollection of a basic technique for playing the villain in melodrama is worth quoting at length (1937, 18-19): "The small fry in the Old Bowery gallery had strict theories of how the villain ought to die, when the hero did him in in the final scene. The old melodrama villains had a specialized technique for kicking the bucket—elbows stiff, spine rigid, then fall over backward square on the back of your head. It took skill to do it right and not kill yourself in good earnest. We all practiced it—I've spent hours bruising myself to a pulp practicing a villain's fall. And we valued villains in direct proportion to the stiffness of their falls. When J. B. Studley, a fine old-time actor, started doing villains at the Old Bowery and tried dying like a human being—a natural sprawling collapse—the whole house came right over the footlights at him with hisses and cat-calls and roars of protest—they wanted a real fall. It wasn't till Studley had learned to stiffen up and crash in the conventional way—and he got to be one of the best fallers in the business—that they'd tolerate him at all."
The Historical Dictionary of the American Theater. James Fisher.