By Sean McKenna:

I had at one time designed to write a piece on the guest characters in the Star Trek films. After some time, I decided that I might have already spent my allotment of tedium writing ad nausea about Voyager, and so I paired down the piece to, well, a pair of guest stars. They happen to come from the first and latest films.

Before I get into them, a little more preamble. Star Trek has always incorporated characters of a singular quality into the televised adventures. This is the outsider, the one who is not like the rest but who nonetheless serves to comment on human nature in often ways more piercing than the actual humans ever manage. It is a tradition begun with Spock, and purposefully carried on down by Data, Odo, Seven, and Phlox (although The Doctor and T’Pol could just as easily be substituted, or seen as complimenting, the final two). When the franchise branched out into film, the characters were transplanted, and although Spock and Data could be said to continue the tradition in this new medium, another tradition would seem necessary as well.

Most films do not center themselves on a pack of crewmates, certainly not film series, which for the most part stick together for the entirety of the film. One of the challenges in creating a Star Trek film is trying to fight the sense that it is nothing more than an extended episode of the more established television variety. To set it apart, strong guest characters, those who are not members of the family that is the featured crew, must be presented, with the intention being that they will carry a portion approaching that of the main characters. The Wrath of Khan might have done it most boldly with Carol and David Marcus, who were intimately related to Captain Kirk; as a former lover and as a product of that love, and both as symbols of the life Kirk has always denied himself. This subject alone could warrant its own article.

Then there's Saavik in The Search for Spock, who is awarded the honor of performing the physical rescue of a beloved main character. Gillian Taylor more than holds her own against Kirk in The Voyage Home, while Sybok acts as the first villain in a Star Trek film to also be cast as ostensibly a benevolent guest character in The Final Frontier, appearing first and foremost as Spock's troubled brother. He's a portent of one of this article's featured characters. Valeris is another troubled Vulcan in The Undiscovered Country who acts as both emotional compatriot and ideological foe. Guinan is the first guest character to have been a regular recurring star in a Star Trek series when she appears in Generations, acting as a wrinkle in time between Kirk and Picard. Lily takes on a burden some have argued Beverly Crusher should have had in First Contact. Admiral Dougherty continues the tradition of the Vulcans in Insurrection.

There are of course other guest characters, not the least being the villains. But those who serve to challenge our main characters, to engage them most directly, are the concern here.

Captain Willard Decker achieves the impossible in The Motion Picture. He makes Kirk look like the bad guy. This might unconsciously be one of the reasons fans have traditionally rebelled against this film. Decker acts as a wedge between Kirk's career aspirations and his love for the Enterprise; his promotion to the admiralty and what Spock terms in the following, and much more beloved, feature Kirk's "first, best destiny." To get the job back, he assumes command of the ship in time of crisis, out of space dock where the ship has had a massive refit that has transformed it out of recognition for Kirk. But not for Decker, who has overseen it and is slated to command it upon relaunch.

Kirk's old friend McCoy tries to make him see what the conflict is, why he and Decker are clashing on the bridge. But Kirk will have nothing of it. He also won't be having the support of his other old friend Spock, who has grown remote in his quest to purge the remainder of his emotions. Decker has a love aboard the ship, the navigator Ilia, who in different times would be the subject of Kirk's own affections. When the mysterious V'Ger claims Ilia and then sends back a copy of her, it's Decker who is put in charge of trying to reacquaint her with her humanoid nature. Kirk is left to try and pick up the pieces, reach Spock and figure out how to resolve the crisis at hand.

When it's Decker who ultimately solves their troubles by merging with the Ilia duplicate to give V'Ger its desired touch of the creator, the biggest blow is handed to Kirk's ego. He isn't the hero; he isn't the one who saves the day. The effect of this is felt most keenly by the viewer, who has for three seasons of television adventures known Kirk to always win. He might have won this time, but not by his own hand. He has been rendered fallible. Decker could not be a stronger guest character. On television, he would have been an unlikely figure. In film, he becomes a measuring stick for all those who would follow.

Nine films later, we arrive at a similar character, although somewhat the reverse. B-4 is an android, created by Dr. Soong in his own image. But he is not unique in that regard. On television viewers have been treated to the malicious Lore several times already and Lore is brother to Data, a main character from The Next Generation and the one besides Picard that the four most recent films have most used. In Nemesis, Brent Spiner achieves a milestone when he both stars and co-stars in a Star Trek film. It is a first, and he is required to carry the bulk of the guest star thrust of the film. There's also Shinzon's Viceroy, who plays a dialogue-minimal role, and Commander Donatra, who has an important but in terms of screen time negligible part. Shinzon himself is a character in the vein of Sybok, but the presence of B-4 lifts the burden of carrying multiple roles.

As Picard struggles with the nature of Shinzon, B-4 is meant to be a not-so-subtle echo, playing off the character arc Data has been on since "Encounter at Farpoint." Data has always strived to become more than the sum of his parts, to become "more human," as he liked to put it. B-4, however, with his more primitive cognitive capabilities, appears to not only be a simpleton, but content to be one. He never struggles against it during the course of the film. His ignorance is never cause to learn, to grow. Whenever Data made a mistake, he attempted to learn from it. While this never altered his child-like obliviousness to how he related to the world around him, it did give him cause for contemplation, introspection.

The end of the film offers some hope, when the memories that Data had downloaded to his brother, in an effort to jumpstart his curiosity, begin to surface in a song, music having been one of Data's fondest forms of expression. If Picard was never able to reach Shinzon, Data had managed a success with B-4. For the grieving captain, this is a note of redemption: that the quality of life he has always held dear, which his lost friend Data so embodied, continues on. We can better ourselves.

For the guest characters in Star Trek films, it is change that they most embody. They are there to give our heroes a nudge in the right direction. Sometimes our heroes have the good sense to know when not to follow, as with Spock and Sybok, and sometimes they know when to listen, as with Lily and Picard. The lessons Decker and B-4 represent are perhaps the most bitter, but in the end most rewarding. Following the V'Ger encounter, it can be said that Kirk embraced life with a renewed vigor. Oh sure, he might have needed an additional, tragic, nudge, in the death of his son, but it was in his most lonely hour, when he had lost sight of the balance that completed his life, that he needed Decker to point him in the right direction. Data was at his most selfless, and it could be said, human, when he had the image of what he had long ago left behind before him.

They might have been the odd men out, but they were all the more necessary for it.