Tibor Kozma (1909 - 24 March 1976) was an American conductor, pianist, accompanist, and vocal coach of Hungarian birth.
 He began his career as an opera conductor in Europe and Ecuador before emigrating to the United States in 1941; ultimately becoming a United States citizen in 1945.
 He worked as a conductor, accompanist, and vocal coach in New York City during the 1940s and 1950s, notably serving on the conducting staff of the Metropolitan Opera from 1950-1957.
 He then had a successful teaching career at the Jacobs School of Music at Indiana University from 1957 until his death 19 years later.
Selim Gustaf Adolf Palmgren (16 February 1878 – 13 December 1951) was a Finnish composer, pianist, and conductor.
 Palmgren was born in Pori, Finland, February 16, 1878.
 He studied at the Conservatory in Helsinki from 1895 to 1899, then continued his piano studies in Berlin with Ansorge, Berger and Busoni.
 He conducted choral and orchestral societies in his own country and made several very successful concert tours as a pianist in the principal cities of Finland and Scandinavia, appearing also as a visiting conductor.
 In 1921, he went to the United States, where he taught composition at the Eastman School of Music, later returning to Finland, where he died in Helsinki, aged 73.
Rudy Toth (16 December 1925 – 9 July 2009) was a Canadian composer, arranger, conductor, pianist, and cimbalom player of Czech birth.
 As a composer he wrote works mainly for television and the radio, working frequently for the Canadian Broadcasting Company for over three decades.
 As a pianist he performed in a number of jazz and dance bands in Toronto and played for radio productions at the CBC.
 For many years he was active as a concert cimbalon player, appearing as a soloist with symphony orchestras in both Canada and the United States.
Børge Rosenbaum (3 January 1909 – 23 December 2000), known professionally as Victor Borge ( ), was a Danish and American comedian, conductor, and pianist who achieved great popularity in radio and television in the United States and Europe.
 His blend of music and comedy earned him the nicknames "The Clown Prince of Denmark," "The Unmelancholy Dane," and "The Great Dane."
Vivian Della Chiesa (October 9, 1915 – January 6, 2009) was an American lyric soprano who achieved a high level of popularity in the United States singing on the radio during the 1940s and the early 1950s.
 She performed a wide variety of classical and popular works from opera to musical theatre, jazz, and popular songs.
 She sang on a number of radio programs during her career, including "The American Album of Familiar Music", "The American Melody Hour", and "The Standard Hour" among others.
 A particularly important triumph for her radio career was a 1943 radio concert of Brahms’s "Deutsches Requiem" with conductor Arturo Toscanini and the NBC Symphony Orchestra.
 In addition to her radio career, Della Chiesa performed actively on the opera stage, mostly at the Chicago City Opera Company and the Chicago Opera Company, during the 1930s and 1940s.
 In the 1950s, she became a successful nightclub singer, headlining at major clubs in Las Vegas, Reno, and in major venues in other cities throughout the United States.
 After her singing career ended she worked as a voice teacher and a fundraiser for charity.
Marcelle de Manziarly (born 1/13 October 1899, Kharkiv, Ukraine, then in Russian Empire - died 12 May 1989) was a French pianist, music educator, conductor and composer.
 She was born in Kharkiv, studied in Paris with Nadia Boulanger and at the age of 23 had already composed two mature works.
 She later studied conducting with Felix Weingartner in Basle and piano with Isabelle Vengerova in New York City and taught and performed in Europe and the United States.
 Aaron Copland dedicated his song "Heart, We Will Forget Him" to her.
 She died in Ojai, California.
John Balme is an American conductor, opera manager and pianist.
 He served as general director of Boston Lyric Opera from 1979 to 1989 and the Lake George Opera Festival from 1988 to 1992.
 he was also music director of the Liederkranz Foundation of the City of New York with a 15-year tenure from 1984 to 1998.
 He has participated as conductor, assistant conductor, and/or producer in over 300 productions and has appeared as a guest conductor throughout the United States.
 He is best known for producing and conducting of the complete "Ring Cycle" of Richard Wagner for the Boston Lyric Opera in Boston and New York City in 1982 and 1983.
The Hobart Arena is a 3,782-seat multi-purpose arena in Troy, Ohio.
 It officially opened with 10 sold out performances of Holiday on Ice in September 1950.
 The Hobart Arena, contrary to popular belief, was not the first Ohio venue for Elvis Presley on November 24, 1956, as he had played in Cleveland a year earlier.
 The 1950s also saw performances by Roy Rogers, Gene Autry, Nat King Cole, Tex Ritter, Sonja Henie, Victor Borge, Liberace, Guy Lombardo, and Patti Page.
George Greeley (born Georgio Guariglia; July 23, 1917 – May 26, 2007) was an Italian-American pianist, conductor, composer, arranger, recording artist and record producer who is known for his extensive work across the spectrum of the entertainment industry.
 Starting as an arranger and pianist with several notable big bands in the 1940s, he segued into the Hollywood radio scene, working on several nationally-broadcast variety programs.
 After conducting an Army Air Force Band during World War II, he was hired by Columbia Pictures as a staff pianist and orchestrator.
 He worked as pianist on several hundred motion pictures, worked with many famous composers orchestrating their soundtrack compositions, and created original compositions of his own in several dozen movies.
 It was Greeley's hands that performed the piano parts that Tyrone Power mimed in "The Eddy Duchin Story."
 Concurrent with his work at Columbia Pictures, George Greeley also worked at Capitol Records as music director, pianist, and conductor for many artists such as Gordon MacRae, Jane Powell, Jo Stafford, Frankie Laine, and Doris Day.
 He was hired in the late 1950s by the newly established Warner Brothers Records.
 George Greeley arranged, orchestrated and performed as primary artist for a series of hit recordings entitled "Popular Piano Concertos."
 As music tastes changed in the late 1960s, Greeley had already moved into television, composing themes and music for popular TV series like "My Favorite Martian," "The Ghost and Mrs. Muir," "Nanny and the Professor," and "Small Wonder."
 He performed as featured piano soloist and as guest conductor in concert appearances around the world.
 George Greeley died from emphysema at age 89 in Los Angeles, California.
John Herbert "Jackie" Gleason (February 26, 1916June 24, 1987) was an American comedian, actor, writer, composer and conductor who developed a style and characters in his career from growing up in Brooklyn, New York.
 He was known for his brash visual and verbal comedy style, exemplified by his bus driver character Ralph Kramden in the television series "The Honeymooners".
 By filming the episodes with Electronicams, Gleason was later able to release the series in syndication, which increased its popularity over the years with new audiences.
 He also developed "The Jackie Gleason Show," which maintained high ratings from the mid-1950s until its cancellation in 1970.
 After originating in Hollywood, filming moved to Miami, Florida, in 1964 after Gleason took up permanent residence there.

Question: When did a Danish and American comedian, conductor, and pianist died who hadgreat popularity in radio and television in the United States and Europe in 1950s?
Answer: 23 December 2000