...Chekov, who apparently is still a cadet (since we see him in a cadet uniform in the crowd at the medal ceremony at the end of the movie)...
Which is somewhat odd, given that it appeared that Chekov, Sulu, Pike, and probably Spock were the only regulars who were part of the initial intended crew. Sulu seems to know why he was subbed in for the regular helmsman, suggesting he didn't just walk off a shuttle and have someone point him to the bridge and Chekov, amazingly, actually seemed to be supposed to be there, since Pike knows him by reputation and (more or less) name.
It was sort of implied that they were nearing the end of the term, so it may have been that Pike had filled out his roster on the Enterprise with anticipated graduates, since they would've been commissioned by the time the launch date rolled around. That splits the difference between the implications about Sulu and Chekov being regular crew and them being in the cadet line at the end.