After his feature debut in "Guns of the Magnificent Seven" (1969), Casey continued to play supporting roles until the "blaxploitation" cycle provided his first leads. He played opposite Pam Grier in "Hit Man" (1972), as a righteously vengeful hood. As the romantic interest of the karate-chopping "Cleopatra Jones" (1973), Casey was the virtuous head of a ghetto halfway house while the well-intentioned but poorly executed biopic "Maurie/Big Mo" (1973) found him playing a paralyzed basketball star. Surprisingly, the improbably titled "Dr. Black, Mr. Hyde" (1975) afforded a strong role as a well-to-do research scientist whose experiments transform him into an albino monster that preys on prostitutes in Watts.
Casey provided sturdy support in more mainstream fare, including Martin Scorsese's first studio effort, "Boxcar Bertha" (1972), Nicolas Roeg's "The Man Who Fell to Earth" (1976) and Burt Reynolds' "Sharkey's Machine" (1981). He was an impressive Felix Leiter to Sean Connery's James Bond in the zesty "Never Say Never Again" (1983). Also adept at comedy, Casey headed the tolerant all-black fraternity in "Revenge of the Nerds" (1983) and its subsequent made-for-TV sequels on the Fox network. He also proved formidable as the no-nonsense history teacher in "Bill and Ted's Excellent Adventure" (1989). A good sport, Casey parodied his earlier roles by playing a retired supercop in Keenan Ivory Wayan's hilarious send-up of "blaxploitation" movies, "I'm Gonna Git You Sucka" (1989). More recently, he has favored action and fantasy (e.g., "Another 48 Hours" 1990; "Under Siege" 1992; and "In the Mouth of Madness" 1995) for his mainstream Hollywood assignments while offering more subtle characterizations for worthy independent fare: the dedicated activist attorney in Charles Burnett's "The Glass Shield" and an upstanding member of a black rural community in the 40s South in Tim Reid's "Once Upon a Time. . . When We Were Colored" (both 1995).
Casey has also worked in TV since the beginning of his career. He was a football player in the acclaimed telepic "Brian's Song" (ABC, 1971), the head gargoyle in "Gargoyles" (CBS, 1972) and joined the all-star black ensembles of the miniseries "Roots: The next Generations" (ABC, 1979) and "The Sophisticated Gents" (NBC, 1991). In 1979, Casey starred in the short-lived "Harris and Company", reputedly one of TV's first attempts to portray black family life on a dramatic series. He continues to make occasional guest shots.