Mr. & Mrs. Smith font here refers to the font used in the poster of Mr. & Mrs. Smith, which is an American romantic comedy action movie released in 2005. The movie centers on a bored married couple, who learn that they are both assassins hired by competing agencies to kill each other.
The font used for the movie title in the poster resembles Classical Garamond Regular. But the ampersand symbol (&) is a different one, which could be derived from a font named Chasseur BQ Regular. Both are available as commercial fonts and you can view details about them here and here respectively.
Download Mr. & Mrs. Smith Font
We are currently unable to find a free alternative or a font similar to the commercial font identified above, and you will need to follow the relevant links above and purchase the font.