Jeffrey Duncan Jones (born September 28, 1946, 6 feet 4 inches [1.94 m]) is an American character actor, best known for his roles as Emperor Joseph II in Amadeus (1984), Edward R. Rooney in Ferris Bueller's Day Off (1986), Charles Deetz in Beetlejuice (1988), Dr. Skip Tyler in The Hunt for Red October (1990), Eddie Barzoon in The Devil's Advocate (1997), and A. W. Merrick in both Deadwood (2004–2006) and Deadwood: The Movie (2019).

Jones was born in Buffalo, New York, and studied acting at the Putney School, the London Academy of Music and Dramatic Art, and Lawrence University. He began his acting career in small parts in film and television in the 1970s. In his best-known roles as Emperor Joseph II in Amadeus, Charles Deetz in Beetlejuice, and Edward R. Rooney in Ferris Bueller's Day Off, his dead-pan expression and distinctive face bring a comic flavor to his characters through their reactions to the situations in which they find themselves, more so than the wit in their scripted lines.

Jones has also had a successful career on stage, appearing in productions of The Crucible, The Importance of Being Earnest, and The Glass Menagerie. He has been nominated for two Tony Awards, for Best Featured Actor in a Play for his performance in The Crucible (1988) and Best Featured Actor in a Musical for his performance in The Secret Garden (1991).

In 2002, Jones was arrested on charges of child pornography. He pleaded guilty to one count of possession of child pornography and was sentenced to two years of probation. He has not appeared in any major film or television roles since his arrest.

Despite his personal troubles, Jones is still considered to be one of the most talented character actors of his generation