Trevor Llewellyn was a Welsh professional heavyweight boxer.
 Born in Newport in Monmouthshire, Llewellyn became the Welsh heavyweight champion in 1922.
 A police officer by profession, he often fought under the name PC Trevor Llewellyn.
Charlotte Wilder (1898–1980) was an American poet and the eldest sister of author Thornton Wilder, Isabel Wilder, Janet Wilder Dakin, and Amos Wilder.
Richard Dafydd Vivian Llewellyn Lloyd (8 December 1906 – 30 November 1983), known by his pen name Richard Llewellyn, was a British novelist.
How Green Was My Valley is a 1939 novel by Richard Llewellyn, narrated by Huw Morgan, the main character, about his Welsh family and the mining community in which they live.
 The author had claimed that he based the book on his own personal experiences but this was found to be untrue after his death; Llewellyn was English-born and spent little time in Wales, though he was of Welsh descent.
 Llewellyn gathered material for the novel from conversations with local mining families in Gilfach Goch.
Thornton Niven Wilder (April 17, 1897 – December 7, 1975) was an American playwright and novelist.
 He won three Pulitzer Prizes—for the novel "The Bridge of San Luis Rey" and for the two plays "Our Town" and "The Skin of Our Teeth" — and a U.S. National Book Award for the novel "The Eighth Day".
Our Town is a 1940 American drama romance film adaptation of a play of the same name by Thornton Wilder starring Martha Scott as Emily Webb, and William Holden as George Gibbs.
 The cast also included Fay Bainter, Beulah Bondi, Thomas Mitchell, Guy Kibbee and Frank Craven.
 It was adapted by Harry Chandlee, Craven and Wilder, and directed by Sam Wood.
The Eighth Day is a 1967 novel by Thornton Wilder.
 Set in a mining town in southern Illinois, the plot revolves around John Barrington Ashley, who is accused of murdering his neighbor Breckenridge Lansing.
 The novel was written over the course of twenty months while Wilder was living alone in Douglas, Arizona.
 "The Eighth Day" was the 1968 winner of the National Book Award.
Hello, Dolly!
 is a 1964 musical with lyrics and music by Jerry Herman and a book by Michael Stewart, based on Thornton Wilder's 1938 farce "The Merchant of Yonkers", which Wilder revised and retitled "The Matchmaker" in 1955.
 The musical follows the story of Dolly Levi (a strong-willed matchmaker), as she travels to Yonkers, New York, to find a match for the miserly "well-known unmarried half-a-millionaire" Horace Vandergelder.
 In doing so she convinces his niece, his niece's intended, and Horace's two clerks to travel to New York City.
Janet Wilder Dakin (June 3, 1910 - October 7, 1994), was a philanthropist, zoologist and a younger sister of author Thornton Wilder and poet Charlotte Wilder.
The Merchant of Yonkers is a play by Thornton Wilder.
 The play had its origins in an 1835 one-act farce by the English dramatist John Oxenford.
 Oxenford's work, "A Day Well Spent", was later extended into a full-length play entitled "Einen Jux will er sich machen" ("He Will Go on a Spree" or "He'll Have Himself a Good Time") by Austrian playwright Johann Nestroy in 1842.
 Wilder adapted Nestroy's version into an Americanized comedy entitled "The Merchant of Yonkers", which revolves around Horace Vandergelder, a wealthy Yonkers, New York businessman in the market for a wife.

Question: What profession does Thornton Wilder and Richard Llewellyn have in common?
Answer: novelist