Has eight films on the American Film Institute's list of the 100 Funniest Movies: Bringing Up Baby (1938) at #14, The Philadelphia Story (1940) at #15, His Girl Friday (1940) at #19, Arsenic and Old Lace (1944) at #30, Topper (1937) at #60, The Awful Truth (1937) at #68, Mr. Blandings Builds His Dream House (1948) at #72 and She Done Him Wrong (1933) at #75.
Hated his performance in Arsenic and Old Lace (1944), saying it was way too over the top and that it was his least favorite film.
He actively sought James Stewart's role in Bell Book and Candle (1958), and Clark Gable's role in Teacher's Pet (1958).
He always wore a gold chain around his neck with three charms attached. The three charms represented the religions of each of his former wives: a St. Christopher for Virginia Cherrill (Roman Catholic), a small cross for Barbara Hutton and Betsy Drake (Protestants), and a Star of David for Dyan Cannon (Jewish. (Donaldson)
He and his fifth wife Barbara Harris renewed their wedding vows on 11 April 1986, the fifth anniversary of their marriage.
He became an American Citizen on June 26, 1942, under naturalization certificate #5502057.
He can be seen in the audience and backstage in the Elvis Presley concert documentary Elvis: That's the Way It Is (1970).
He considered himself to be miscast in The Howards of Virginia (1940), None But the Lonely Heart (1944) and The Pride and the Passion (1957).
He gave his entire fee for The Philadelphia Story (1940) to the British war effort.
He gave serious consideration to retiring in 1953, because he believed the success of Marlon Brando and Method acting meant his own kind of acting was a thing of the past. Eighteen months later he was lured back to make To Catch a Thief (1955), and therefore delayed his retirement until 1966.
He had one of his daughter Jennifer's first baby teeth encased in Lucite.
He initially decided to end his 1953 retirement just to make To Catch a Thief (1955). When the film proved to be a huge success he agreed to make further films.
He kept himself slender and fit until he retired acting, never weighing above 180 pounds.
He never played a villain.
He never said "Judy, Judy, Judy" in the movies, which he credits to Larry Storch, but he did say "Susan, Susan, Susan" in Bringing Up Baby (1938).
He once phoned hotel mogul Conrad Hilton in Istanbul, Turkey, to find out why his breakfast order at the Plaza Hotel, which called for muffins, came with only one and a half English muffins instead of two. When Grant insisted that the explanation (a hotel efficiency report had found that most people ate only three of the four halves brought to them) still resulted in being cheated out of a half, the Plaza Hotel changed its policy and began serving two complete muffins with breakfast. From then on, Grant often spoke of forming an English Muffin-Lovers Society, members of which would be required to report any hotel or restaurant that listed muffins on the menu and then served fewer than two.
He remained close to Barbara Hutton's son Lance Reventlow after their divorce. The boy regularly stayed with Grant on some weekends. Grant referred to him as his son, was devastated when he died in a plane crash and helped Barbara with the funeral arrangements.
He strongly disliked Method acting.
He turned down the role of Professor Henry Higgins in My Fair Lady (1964) because he felt he would either not be as good as Rex Harrison, who had originated the part on the London stage and on Broadway, or he would be accused of imitating Harrison. He told producer Jack L. Warner that unless Harrison was cast, he would not even go to see the film.
He voted for Richard Nixon in 1968 and 1972, Gerald Ford in 1976 and Ronald Reagan in 1980 and 1984.