Summary
Commander Riker was initially known as "Bill" in the Star Trek: The Next Generation bible, resulting in Dr. Crusher addressing him as "Bill" in the "Worst Contact" episode of the Short Treks series.
Commander Riker's nickname "Will" quickly emerged in the series, possibly influenced by William Shatner, who is affectionately called "Bill" by his close friends. Initially, Riker was intended to embody the TNG version of James T. Kirk.
Throughout the course of Star Trek: The Next Generation, Riker underwent noteworthy transformations, notably sporting his iconic beard in season 2. However, following the first season, he was never referred to as "Bill" again. Ultimately, he married Counselor Troi and ascended to the rank of Captain, commanding the USS Titan.
In an episode of Star Trek called "Worst Contact," there is a peculiar mistake that turns out to be a clever reference from an earlier episode of Star Trek: The Next Generation. Commander William T. Riker and Dr. Beverly Crusher attempt a First Contact with an alien race, which takes an unexpected and revolting turn. Although this particular episode is not considered official Star Trek canon, there is a curious moment where Crusher addresses Riker as "Bill" instead of "Will."
Responding to curious fans who questioned this discrepancy, Twitter user Ryan Thomas Riddle, @ryantriddle, pointed out that the original bible for the first season of Star Trek: The Next Generation revealed that Riker was initially intended to be nicknamed "Bill" instead of "Will." Take a look at his post below for more information.
How "Bill" Riker Changed In Star Trek: The Next Generation
The Star Trek: TNG bible served as an initial portrayal of Commander William Riker, who took on the title of "Number One" after the abandonment of the previous character, also known as Number One, portrayed by Majel Barrett in the original Star Trek pilot episode, "The Cage." Naturally, the character of Riker underwent transformations following the casting of Jonathan Frakes and throughout the 7-season run of TNG.
Commander William T. Riker underwent considerable changes throughout Star Trek: The Next Generation. While his Imzadi, Counselor Deanna Troi (Marina Sirtis), did refer to Riker as "Bill" once in TNG episode 3, "The Naked Now," his nickname quickly evolved into the more familiar Will. This shift may have been influenced by how William Shatner, Riker's predecessor as Captain Kirk, is affectionately called Bill by his close friends. Riker's initial conception as TNG's counterpart to Kirk might have also played a role in this transition.
In TNG season 2, Jonathan Frakes sported a beard that became Will Riker's iconic trademark. While Riker had a reputation as a ladies' man, his true and only love was Troi. They eventually tied the knot in Star Trek: Nemesis and went on to start a family, as seen in Star Trek: Picard. Another significant development in Riker's story was the appearance of his identical clone, Thomas Riker, who was last seen in Star Trek: Deep Space Nine. Despite brief periods as Acting Captain, Riker never had the opportunity to officially assume command of the Enterprise. Instead, he took on the role of Captain of the USS Titan. Interestingly, after the first season of Star Trek: The Next Generation, Riker was never again referred to as "Bill".