Leonard Monduran Landsborough (August 7, 1857 – March 14, 1927) was an American agriculturist in the Florin, California, area and a member of the California State Assembly.
A member of the Populist Party and then a Democrat, he was active in a movement to protect the rights of Japanese farmers in the Sacramento Valley.
He resigned from the Assembly after being indicted for malfeasance while he had been a Sacramento County employee, but was acquitted of all charges.