William T. Riker was a clone of William T. Riker created from his epithelial cells, against his will, by the Mariposans in 2365.
Later when this clone and a Katherine Pulaski clone were discovered by Riker, Pulaski, and Geordi La Forge, Riker vaporized them both with a phaser. (TNG: "Up The Long Ladder")
This version of Riker was described in the script as "a half-formed clone, but it is still recognizably the first officer."