Question: Did Larry Hagman and Fred de Cordova both act in the show "Dallas"? 

Context articles: The Countess of Monte Cristo (1948 film)
Rudolph de Cordova
The Bing Crosby Show (film)
Bedtime for Bonzo
Alonso de Cordova y Figueroa
De Cordova Bend Dam
J. R. Ewing
Larry Hagman
Fred de Cordova
Leander de Cordova

The Countess of Monte Cristo is a 1948 American comedy film directed by Fred de Cordova and starring Sonja Henie, Olga San Juan and Dorothy Hart.
Rudolph de Cordova (1860–1941) was a Jamaican-born British writer, screenwriter and actor.
 He was married to the writer Alicia Ramsey and collaborated with her on several plays.
 Cordova was born in Kingston, the son of a prominent merchant.
 He went to London to study medicine in the 1880s, but soon abandoned his studies in order to become an actor.
 His brother was the actor and film director Leander de Cordova.
The Bing Crosby Show was Bing Crosby's first television special.
 Directed by Fred de Cordova, it originally aired in the United States on January 3, 1954.
 Guest stars included Jack Benny and Sheree North, with Ken Carpenter as the announcer.
Bedtime for Bonzo is a 1951 comedy film directed by Fred de Cordova, starring Ronald Reagan, Diana Lynn, and Peggy as Bonzo.
 It revolves around the attempts of the central character, psychology professor Peter Boyd (Ronald Reagan), to teach human morals to a chimpanzee, hoping to solve the "nature versus nurture" question.
 He hires a woman, Jane Linden (Diana Lynn), to pose as the chimp's mother while he plays father to it, and uses 1950s-era child rearing techniques.
Alonso de Cordova y Figueroa (?
 - August 9, 1698) Spanish soldier born in Concepción, Chile, son of Alonso de Figueroa y Córdoba and father of the historian Pedro de Cordova y Figueroa.
 He served as lieutenant, captain of infantry and of cavalry in Lota and San Carlos de Austria; lieutenant general of cavalry and Sargento Mayor of the Captaincy General of Chile.
The De Cordova Bend Dam is a man-made dam on the Brazos River in Hood County, Texas, United States, controlled by the Brazos River Authority.
 De Cordova Bend Dam forms the 8300 acre Lake Granbury.
 The dam is so named because of the clockwise almost-complete loop in the Brazos River named De Cordova Bend after Jacob De Cordova.
John Ross "J. R." Ewing Jr. is a fictional character in the U.S. television series "Dallas" (1978–91) and its spin-offs, including the revived "Dallas" series (2012–14).
 The character was portrayed by Larry Hagman from the series premiere in 1978 until his death in late 2012, and Hagman was the only actor who appeared in all 357 episodes of the original series.
 As the show's most famous character, J. R. has been central to many of the series' biggest storylines.
 He is depicted as a covetous, egocentric, manipulative and amoral oil baron with psychopathic tendencies, who is constantly plotting subterfuges to plunder his foes' wealth.
Larry Martin Hagman (September 21, 1931 November 23, 2012) was an American film and television actor, director and producer best known for playing ruthless oil baron J.R. Ewing in the 1980s primetime television soap opera "Dallas" and befuddled astronaut Major Anthony "Tony" Nelson in the 1960s sitcom, "I Dream of Jeannie".
Frederick Timmins "Fred" de Cordova (October 27, 1910 – September 15, 2001) was an American stage, motion picture and television director and producer.
 He is best known for his work on "The Tonight Show Starring Johnny Carson".
Leander de Cordova (1877–1969) was a Jamaican actor and film director.
 He was the brother of Rudolph de Cordova.