Which actor from the Harry Potter series is in a movie with Will Smith?

Kenneth Branagh is Gilderoy Lockhart in "Harry Potter and the Chamber of Secrets". He is also Dr. Arliss Loveless in "Wild Wild West", with Will Smith.

Kenneth Branagh started his acting career on stage, with the Royal Shakespeare Company. After deciding the RSC was too large and impersonal, he opened his own, called the Renaissance Theatre Company, of which Prince Charles is a royal patron.

In the '80s, Branagh switched to camera. He acts in a variety of movies, as well as directing and producing some. He has also written some, mostly Shakespeare adaptations.

After the success of "Murder on the Orient Express", he will be Agatha Christie's detective again. "Death on the Nile" is scheduled to come out in 2020, starring Kenneth Branagh as Hercule Poirot. Branagh starred and directed the first, and will do the same for the second.