Despite fan speculations about his return to the franchise, William Shatner confirmed that he will not appear in Star Trek Beyond.
With Star Trek Beyond being released during the year of Star Trek's 50th anniversary, some fans speculated that Shatner would reprise his role as Captain Kirk just as Leondard Nimoy reprised his role as Spock in Star Trek (2009) and Star Trek Into Darkness. There were rumors that suggested that Kirk would be seen with Leonard Nimoy as the original Spock, prior to Nimoy's death in 2015. Shatner even confirmed that idea, but now he says that he's no longer involved:
"There was never a conversation," Shatner tells SFX Magazine
Shatner last played Kirk in 1994's Star Trek: Generations, in which the character died. The actor said that he would be curious to see how the writers would explain him looking 20 years older.
"It would have been interesting to see what their fertile imaginations could have done with somebody who is 20 years older than when Captain Kirk died [in Star Trek Generations] and how they would have explained the difference in appearance. But that never came up. I'm sure they must have thought of it one time or another but I never had a substantial conversation about replaying the role."
There were rumors that said that Kirk was featured prominently in the script written by Star Trek Beyond's original director, Roberto Orci, but that script has since been revised heavily.