Blackmer was born on July 13, 1895 and raised in Salisbury, North Carolina. He started off in an insurance and financial business but gave up on it. While working as a builder's laborer on a new building, he saw a Pearl White serial being filmed and immediately decided to go into acting. He attended the University of North Carolina at Chapel Hill and majored in acting and drama. Blackmer went to New York hoping to act on the stage. While in the city, he took jobs and extra work at various film studios at the then motion picture capital, Fort Lee, New Jersey, including a bit part in the highly popular serial, The Perils of Pauline (1914).
He was a pioneer in the new medium of radio, on which he sang during the 1920s. (Blackmer later participated in the first experimental dramas on Allen B. DuMont's television network.) But it was the movies that increasingly attracted Blackmer's professional attention, in which he typically was cast as a smooth villain from High Society, although he did also play sympathetic roles.
He made his Broadway debut in 1917, but his career was interrupted by service in the U.S. military in World War I. After the war, he returned to the theatre and in 1929 returned to motion pictures and went on to be a major character actor in more than 120 films. Blackmer was one of the Broadway stars who headed West, appearing in his first talkie, "The Love Racket" (1929), in 1929. He starred in other early sound films, including "Kismet" (1930/I), which is considered a lost film. He was memorable as Big Boy in support of Edward G. Robinson in the gangster classic Little Caesar (1931).
Blackmer returned to Broadway in 1931 with the comedy "The Social Register" and appeared again in the comedy "Stop-Over" in 1938. In Hollywood, he had a supporting role in the Robert Donat version of "The Count of Monte Cristo" (1934). Also that year, he appeared in 'William A. Wellman''s "The President Vanishes" (1934), co-starring 'Edward Arnold' and 'Osgood Perkins', the father of 'Anthony Perkins'.
Sidney Blackmer has the distinction of starring in the only movie ever "written" by a president of the United States, "The President's Mystery" (1936), based on a story by "co-authored" by 'Franklin D. Roosevelt'. F.D.R. was an avid murder mystery reader, and at a meeting of whodunit authors at the White House during his first administration, he suggested an idea for a mystery novel to the writers: A millionaire disappears and starts a new life under a new identity, taking his wealth with him. Mystery writers, including S.S. Van Dine, cobbled together a patch-work book of uneven quality based on the premise, with F.D.R. listed as co-author. "The President's Mystery" became a best-seller due to F.D.R.'s enormous personal popularity. In the movie version, written by future Hollywood Ten member 'Lester Cole' and novelist 'Nathanel West', Blackmer played millionaire industrialist Sartos, who engineers his own disappearance while holding on to his fortune. Sartos blackmails a corrupt investment bank run by two con men, which he takes over. He then invests his money with the firm, and robs himself under cover of the crooked brokerage. Disappearing after "losing" his fortune, people believe Sartos has committed suicide. Just when it seems that he has accomplished his goal and has escaped into his new life with his loot, something goes awry.
He won the 1950 Tony Award for Best Actor (Drama) for his role in the Broadway play, Come Back, Little Sheba. He played opposite Shirley Booth in the role of his lifetime. Unfortunately, Blackmer did not star in the movie version in 1953 - he was replaced by Burt Lancaster.
In film, Blackmer is remembered for his more than a dozen portrayals of U.S. President Theodore Roosevelt. The role I remember him most in the the MGM musical High Society (1956) where he plays Seth Lord, Grace Kelly's estranged father. He did not sing in the film, but it was the first movie I saw him in. However, his best remembered role was his role in the Academy Award-winning 1968 Roman Polanski film about urban New York witches, Rosemary's Baby, in which he played an over-solicitous neighbor.
Sidney was not only an actor ,but he was involved in many important causes. In 1919, Blackmer played a major role in the strike that led to the formation of Actors' Equity Association. A humanitarian, Blackmer served as the national vice president of the United States Muscular Dystrophy Association. He also helped start up the North Carolina School of the Arts. In 1972, he was honored with the North Carolina Award in the Fine Arts category. It is the state of North Carolina's highest civilian award. On his passing in 1973, Blackmer was interred in the Chestnut Hill Cemetery in his hometown of Salisbury, North Carolina.
Blackmer was married to actress Lenore Ulric from 1928–1939. His second wife was Suzanne Kaaren to whom he was married from 1943 to his death in 1973. She passed away in 2004 at the age of 92. He and Kaaren had two sons. Sidney Blackmer died of cancer on October 6, 1973 at the age of 78 in New York City. He was interred in Chestnut Hill Cemetery in his home town of Salisbury, NC...