Jonathan Frakes just returned as Will Riker this year in Star Trek: Picard, the first time he’d reprised the role in 15 years. But, in another timeline, Riker could’ve been killed off during Star Trek: The Next Generation and Frakes would’ve been playing Riker’s doppelgänger Thomas ever since.
In season 6’s “Second Chances,” the Enterprise-D crew discover that a transporter accident several years ago created a double of Riker. While he beamed back aboard the U.S.S. Potemkin, another Riker rematerialized on Nervala IV, where he was eventually discovered and rescued by Picard and co. The episode saw Riker and the rest deal with the sudden appearance of this new Riker, who took the name Thomas, before Picard got him a new posting on the U.S.S. Gandhi.
The original idea for “Second Chances,” however, was for Will to die and for Thomas to replace him, thereby keeping Frakes around but giving him a whole new character to play. Thomas would’ve joined the Operations crew, while Data would’ve been promoted to First Officer. EP Michael Piller vetoed the idea at the time, but this didn’t stop the same thing from being pitched the following season.
This time, Star Trek boss Rick Bergman was the one to pull the plug on the plan, worrying about the repercussions of this on the wider franchise. For instance, the movies would have to explain why Riker was a different character now for audiences not up to date with the show. Instead, Thomas later reappeared on Deep Space Nine, where he ended up sentenced to life imprisonment on a Cardassian labor camp.
Unfortunately, this is the last time we heard from him, as DS9 writers put a ban on future episodes based around the character. Still, Jonathan Frakes likes to think he was involved with the Cardassian resistance during the Dominion Wars. And who knows, now that Picard is bringing back various characters from Star Trek: The Next Generation, Thomas could one day return. After all, Will being killed off and Thomas replacing him seems like just the sort of bold move Picard would pull.