William Riker's estranged father, a civilian strategist whose visit forced the two men to confront years of resentment.
Kyle Riker was a civilian strategic adviser to Starfleet. He raised William alone after his wife died when Will was a child, but he was often absent, and the two had not spoken in years. In The Icarus Factor he came aboard the Enterprise-D to brief Will on a command he had been offered.
Kyle had a past friendship with Dr. Katherine Pulaski. Father and son finally aired their grievances in an anbo-jyutsu match, during which Will discovered that his father had been cheating in their bouts since his childhood. The encounter began to repair their relationship.