Mister Smith
Mister Smith is a term used for male persons whose surname is Smith.
Mister Smith can also mean:

A placeholder name for a generic person (as Smith is a common English surname) - often exemplified as "John Smith"
Mr. Smith (album), a hiphop album by rapper LL Cool J
Mr. Smith (novel), a novel by Louis Bromfield
Mr Smith (The Sarah Jane Adventures), a fictional extraterrestrial computer in the Doctor Who spinoff The Sarah Jane Adventures
Mr. Smith (TV series), a short-lived 1983 sitcom, with a talking orangutan as the title characterAgent Smith, a character in The Matrix, portrayed by Hugo Weaving
SuitSat, a Russian spacesuit nicknamed Mr. Smith by some
Mr. Smith, a character from Call of the Wild
A pen-name used by Ralph Ingersoll Lockwood
Mister Smith Entertainment, a British film company

See also
John Doe
Mr. & Mrs. Smith (disambiguation)
Mr. Smith Goes to Washington, a popular film starring James Stewart