William Marshall William Marshall was an American actor , director , producer , and opera singer who appeared on , playing Doctor Richard Daystrom in the episode . He was the cousin of fellow " Star Trek " actor Paul Winfield . Marshall is perhaps best known for playing the title role of the 1972 cult vampire melodrama , " Blacula " , and its 1973 sequel , " Scream Blacula Scream " . He was also known for his performance as the " King of Cartoons " on the children ' s program " Pee - wee ' s Playhouse " from 1987 through 1991 . Marshall was born in Gary , Indiana , and later lived in Pacoima , California . He was trained as a classical actor as well as an opera singer . He died from complications of Alzheimer ' s disease in Los Angeles , California , at the age of 78 . He died exactly four years after the passing of his TOS co - star DeForest Kelley . Marshall ' s cousin , Paul Winfield , died the following year . Acting career . 1940s - 1960s . In the 1940s , 1950s , and 1960s , Marshall appeared in several stage plays , including Broadway productions of " Carmen Jones " , " Lost in the Stars " ( a later production of which starred Brock Peters ) , and " Peter Pan " ( acting with Nehemiah Persoff ) . He made his film debut as King Dick in 1952 ' s " Lydia Bailey " . This was followed with a supporting role in 1954 ' s " Demetrius and the Gladiators " , co - starring Jay Robinson and featuring Jean Simmons and Julie Newmar . In 1958 , he co - starred with Dame Judith Anderson and Theodore Bikel on the live anthology series " The DuPont Show of the Month " . Marshall played the title role of William Shakespeare ' s " Othello " in several stage productions throughout the 1950s . He also produced the first of these productions at the Mother Zion Church in New York City in 1953 . Marshall later starred in and directed " The Bear and The Marriage Proposal " in 1961 , which toured at various US Army based in France . He also directed the play " Long Voyage Home " at the American Artists and Students Center in Paris , France , in 1962 . From 1962 through 1963 , Marshall toured as Othello in various European cities as part of the Dublin Theatre Festival . Norman Lloyd directed Marshall in a 1964 episode of " Alfred Hitchcock Presents " . That same year , Marshall appeared on the TV series " The Nurses " , starring Stephen Brooks . Also in 1964 , Marshall was seen in an episode of " Bonanza " with Jason Wingreen , an episode of " Rawhide " with Don Marshall ( no relation ) and Harry Townes , and an episode of " The Man from U . N . C . L . E . " with Fritz Weaver . Marshall was then directed by John Meredyth Lucas in a 1965 episode of " Ben Casey " . In 1967 , Marshall acted alongside fellow TOS actors Jason Evers , Lloyd Haynes , and Perry Lopez in various episodes of NBC ' s " Tarzan " . That same year , he co - starred with Lawrence Montaigne in episodes of " Daniel Boone " and " The Man from U . N . C . L . E . " Marshall then had major supporting roles in the 1968 films " To Hell with Heroes " ( directed by Joseph Sargent and co - starring Sid Haig ) and " The Boston Strangler " . The latter film co - starred fellow TOS guest actors Jeff Corey and Sally Kellerman and also featured cinematography by director of photography Richard H . Kline . Marshall was directed by Marvin Chomsky in a 1968 episode of " The Wild Wild West " co - starring Tom Troupe . He then appeared in the CBS / MGM TV pilot movie " U . M . C . " along with Alfred Ryder , William Windom , and Jason Wingreen . 1970s - 1990s . In 1970 , Marshall had a role in the adventure film " Skullduggery " , which starred Roger C . Carmel and featured Booker Bradshaw . That same year , he had a supporting role in the thriller " Zigzag " . Stewart Moss , Steve Ihnat , and Vic Perrin also appeared in this film . In 1971 , Marshall appeared in the film " Honky " , along with John Fiedler , and in 1974 , he starred in the blaxploitation horror film " Abby " , which was co - edited by Bub Asman ( the supervising sound editor on ) . In 1977 , Marshall had a role in the thriller " Twilight ' s Last Gleaming " , along with his cousin , the late Paul Winfield . Possibly Marshall ' s most famous film role was that of Mamuwalde , the African prince who is transformed into the vampire " Blacula " by Count Dracula , in the blaxploitation horror films " Blacula " ( 1972 ) and " Scream , Blacula , Scream " ( 1973 ) . The first film also starred fellow " Star Trek " guest actors Elisha Cook , Jr . , Charles Macaulay , and Thalmus Rasulala . " Blacula " won the " Best Horror Film " award at the 1972 Saturn Awards ; the second film was nominated for the same honor . On television , Marshall guest - starred with Davis Roberts in a 1970 episode of " Insight " and a 1972 episode of " Mannix " ; the latter also featured Dallas Mitchell . He later co - starred with Bernie Casey in a 1977 episode of " Police Woman " . That same year , Marshall was a regular on the short - lived NBC drama series " Rosetti and Ryan " . Marshall reunited with his " Demetrius and the Gladiators " co - star ( and fellow TOS guest star ) Jay Robinson for a stage production of William Shakespeare ' s " Othello " , which was taped and released on video in 1981 . Marshall then guest - starred in an episode of " The Jeffersons " with Keone Young and appeared in the 1983 horror film " Curtains " , starring Samantha Eggar . He later played The Grim Reaper in an episode of " Benson " , the hit comedy series which starred Rene Auberjonois . In 1986 , Marshall had a supporting role in the comedy film " Vasectomy : A Delicate Matter " , starring Paul Sorvino . He then played the pirate captain in the " Video Pirates " segment of the film " Amazon Women on the Moon " . guest star Frank Collison worked with Marshall on this skit , while Ed Begley , Jr . , Ronny Cox , Larry Hankin , Dick Miller , and Robert Picardo appeared in different segments . Marshall began playing the King of Cartoons on " Pee - wee ' s Playhouse " in 1987 , replacing actor Gilbert Lewis . During his segment , Marshall ' s character played a brief cartoon , usually from the " Golden Age " of animation . The King of Cartoons was well - known for introducing each cartoon with his catchphrase " " Let . . . the cartoooon . . . begin ! " " . He played the role until the series concluded in 1991 . More recently , he and fellow " Trek " alumni Henry Darrow and Bert Remsen appeared as poker players in the 1994 film " Maverick " . Marshall then had supporting roles in the cult sexploitation films " Sorceress " ( along with Edward Laurence Albert ) and " Dinosaur Valley Girl " ( with Jeff Rector ) . The latter was Marshall ' s final film .