Not David Niven. He HATED that Peter Sellers stole the original "Pink Panther" movie away from him. Inpector Clouseau was supposed to be a minor character but Sellers did such an incredible job in the role that everybody focused on him. BTW, I read an account of how Sellers got into the character of Inspector Clouseau. He started out with the jacket (and I think the cap) and continuously wore them as he morphed into the character of Clouseau before the filming began.
It reminds me of the scene in "Once Upon A Time In Hollywood" where the Leonardo DiCaprio character reflects on the time he lost the role to Steve McQueen in "The Great Escape"...:)
I love Peter Sellers-this is a collection of his outtakes: LINK: Peter Sellers Pink Panther Outtakes