Matt Decker
Another Commodore from TOS, Matthew Decker appeared in the episode “The Doomsday Machine,” played by William Windom. In that episode, Commodore Decker was commanding the USS Constellation—a sister ship of the Enterprise—and was driven to near-reckless obsession over the destruction wrought by the massive planet killer.
The opportunity for Strange New Worlds would be to show Decker when he is in his prime. Rather than being wracked with grief and guilt, we could see just how exceptional of a leader and officer Decker presumably was.
In fact, an interesting twist could be a situation where Captain Pike—whom we typically know to be very calm and collected—is overcome with emotion and loses his cool, so that Decker is the one who has to help Pike regain control of his emotions. This would be a role reversal of Kirk and Decker’s positions in “The Doomsday Machine.”
Also, an appearance of Matt Decker could allow for an official on-screen confirmation that his son is Will Decker, from Star Trek: The Motion Picture. Although this has been consistently stated across various books and promotional materials, it hasn’t been stated on-screen, so it is not technically canon by certain metrics.
Strange new worlds for existing characters
Overall, I admit that the abundance of pre-existing characters in Strange New Worlds can be tiring. It makes it hard for SNW to have a fully distinct identity in the way that shows like The Next Generation or Deep Space Nine do. It also means that some drama is lost, because we know what happens to over half of the characters.
That being said, it can also be fun to learn new things about characters we already know. By directing some focus onto familiar characters who have very little development, the Strange New Worlds writers could draw connections between SNW and TOS while also adding to the lore of Star Trek without convoluting well-established character backstories.