The Phantom/Sir Charles Lytton

Sir Charles Lytton, also known as the Phantom, is a character in the Pink Panther film series, appearing originally as the protagonist of first film The Pink Panther and then as a supporting character in The Return of the Pink Panther, Trail of the Pink Panther and Curse of the Pink Panther. He is the archnemesis of Jacques Clouseau - who originally appeared as the antagonist of the first film but took over as the protagonist for most of the Pink Panther sequels.

He was played by David Niven in the first film as well as Trial and Curse, with Christopher Plummer appearing as the character in Return.

The Pink Panther (1963)
Sir Charles Lytton is a rich man and playboy who secretly operates as a thief known as "The Phantom", and leaves a calling card in the form of a white glove. He plots to steal the Pink Panther diamond from Princess Dala and ends up staying at a ski resort, where Inspector Clouseau just happens to end up staying at as well, as he has deducted the Phantom will be there. Clouseau has made it his life work to unmask and capture the Phantom. Charles ends up having a love affair with Clouseau's wife, who is secretly in alliance with the Phantom.

In the end Charles, his nephew and Clouseau's wife end up having Clouseau framed as being the Phantom when the Pink Panther diamond is planted on him (with the help of Dala) and he is wisked off to prison whilst the trio drive off. Clouseau would end up being released not long after and returned to the force, although Charles isn't exposed as the Phantom.

Return of the Pink Panther (1975)
Charles has been 'retired' for several years from a life of crime and is instead settled down. But after the Pink Panther diamond is stolen again and his calling card with the white glove is left at the crime scene, Charles begins conducting his own investigation into who is responsible. At the same time, Clouseau is looking into the theft, believing Charles to be up to his old tricks again.

Trail of the Pink Panther (1982)
After the Pink Panther diamond is stolen again, Clouseau goes looking for Charles and ends up traveling to Britain (despite Charles living in the South of France). After Clouseau goes missing after his plane disappears, a reporter Marie Jouvet looks into it interviews those who knew Clouseau, which includes Charles himself. Charles is now married to Clouseau's ex-wife.

Trivia

 * David Niven had played similar characters like Charles Lytoon in other movies before the Pink Panther, which includes A. J. Raffles in the 1939 film Raffles.