The Keller Ferry or Clark Ferry, is a ferry crossing on Franklin D. Roosevelt Lake in the US state of Washington. The crossing carries State Route 21 between the Colville Indian Reservation in Ferry County and Clark in Lincoln County. The ferry has been in operation since the 1890s and under state control since 1930. During that time, five vessels have served the crossing, including the Martha S., which operated from 1948 to 2013, and the current ferry, the M/V Sanpoil.

The U.S. state of Washington is home to a number of public and private ferry systems, most notably the state-run Washington State Ferries.