Question: What is the name of the character played by Peter Sellers in the movie that inspired Mastermind?

Context paragraphs:
The Optimists of Nine Elms: The Optimists of Nine Elms, also known as The Optimists, is a 1973 British drama film starring Peter Sellers and directed by Anthony Simmons, who also wrote the 1964 novel upon which the film is based.  The film is about an old street musician (played by Sellers) who strikes up a friendship with two children - Liz, played by Donna Mullane, and her young brother Mark, played by John Chaffey.  Neither of the child actors were featured in future films.  A young Keith Chegwin also played a small role in the film.

The Magic Christian (novel): The Magic Christian is a 1959 comic novel by American author Terry Southern (1924–1995) about an odd billionaire who spends most of his time playing elaborate practical jokes on people.  It is known for bringing Southern to the attention of filmmaker Stanley Kubrick, who had received a copy as a gift from Peter Sellers, and subsequently hired him as co-writer for "Dr. Strangelove" (1964) when Kubrick decided to make that film a black comedy/satire, rather than a straightforward thriller.  In 1969, "The Magic Christian" was made into a film starring Peter Sellers and Ringo Starr; the story was much altered and relocated from New York City to London.

Mr. Topaze: Mr. Topaze (also known as I Like Money) is Peter Sellers' directorial debut in 1961.  Starring Sellers, Nadia Gray and Leo McKern, as well as Herbert Lom.  His son Michael Sellers plays in the film in the role of Gaston.  The film is based on the eponymous play by Marcel Pagnol.

A Shot in the Dark (1964 film): A Shot in the Dark is a 1964 comedy film directed by Blake Edwards.  It is the second installment in "The Pink Panther" series.  Peter Sellers is featured again as Inspector Jacques Clouseau of the French Sûreté.

The Life and Death of Peter Sellers: The Life and Death of Peter Sellers is a 2004 British-American television film about the life of English comedian Peter Sellers, based on Roger Lewis's book of the same name.  It was directed by Stephen Hopkins and stars Geoffrey Rush as Sellers, Miriam Margolyes as his mother Peg Sellers, Emily Watson as his first wife Anne Howe, Charlize Theron as his second wife Britt Ekland, John Lithgow as Blake Edwards, Stephen Fry as Maurice Woodruff and Stanley Tucci as Stanley Kubrick.

Hoffman (film): Hoffman is a 1970 British film directed by Alvin Rakoff and starring Peter Sellers, Sinéad Cusack, Ruth Dunning and Jeremy Bulloch.  It is the tale of an older man (Peter Sellers) who blackmails an attractive young woman (Sinéad Cusack) into spending a week with him in his flat in London.  His hope is that she will forget her crooked fiancé and fall in love with him instead.

Ruxton Hayward: Ruxton Hayward was a British eccentric.  In the early 1950s, as a scoutmaster in London, he attempted to recruit acts for a stage show.  He approached Michael Bentine, and then, at Bentine's recommendation, Peter Sellers.  Sellers was so taken with Hayward's appearance -- the man being tall with a bushy red beard, and wearing a Boy Scout uniform with short trousers -- that he used an imitation of Hayward's high-pitched voice for the character Bluebottle in "The Goon Show".  The character became a popular regular on the series, and was often greeted by cheers from the audience.

The Fiendish Plot of Dr. Fu Manchu: The Fiendish Plot of Dr. Fu Manchu is a 1980 comedy film, primarily notable as the final film of Peter Sellers, David Tomlinson and John Le Mesurier.  Pre-production began with Richard Quine as director.  By the time the film entered production, Piers Haggard had replaced him.  Peter Sellers handled the re-shoots himself.  Based on characters created by Sax Rohmer, the film stars Sellers in the dual role of Fu Manchu, a stereotypical Chinese evil genius, and English country gentleman detective Nayland Smith.  Released only two weeks after Sellers death, the film was a commercial and critical failure.  It was also the final screen appearance for Tomlinson, who retired from acting shortly before its release.

Trail of the Pink Panther: Trail of the Pink Panther is a 1982 British comedy film starring Peter Sellers for the sixth and final time.  It was the seventh film in "The Pink Panther" series, the first film in the series following Sellers' death and also the last in which he appeared as Inspector Clouseau.  Sellers died before production began.  His performance consists only of deleted scenes from previous films.

Mastermind (film): Mastermind is a Charlie Chan spoof filmed in 1969 that sat on the shelf for seven years before receiving a limited theatrical release in 1976.  It has developed a cult following in recent years since making its home video debut.  The second of producer Malcolm Stuart's two-picture deal with screenwriter, William Peter Blatty, the project was inspired by the success of the 1964 Peter Sellers comedy, A Shot in the Dark which Blatty had co-written with producer/director Blake Edwards.  Blatty's script was drastically revised by Ian McLellan Hunter prior to production and the disgruntled screenwriter chose the pseudonym of Terence Clyne for his screen credit.  By 1973 it had recorded a loss of $2.9 million.  Blatty's original screenplay was published as part of a limited edition collection by Lonely Road Books in 2013 under the title, Five Lost Screenplays by William Peter Blatty.

Supporting paragraphs: Mastermind (film) A Shot in the Dark (1964 film)
Answer: Inspector Jacques Clouseau