John William Leftwich (September 7, 1826 – March 6, 1870) was an American politician and a member of the United States House of Representatives for the 8th congressional district of Tennessee.

He attended public school, studied medicine, and graduated from Philadelphia Medical College in 1850.

He moved to Memphis, Tennessee and engaged in mercantile pursuits.

Upon the readmission of Tennessee to representation, he was elected as an Unionist to the Thirty-ninth Congress.

He served from July 24, 1866 to March 3, 1867 and was an unsuccessful candidate for re-election.