Looking for par’Mach in All the Wrong Places: The Best Non-Recurring Character in Star Trek–Nominations

I think we all know that a tournament to determine the best character in Star Trek would result in nothing but tears, frustration, and victory for a certain half-Vulcan science officer.  Instead, I’m proposing a tournament to determine our favorite single-appearance character in all of Star Trek; those special guest stars who brightened (or darkened) or televisions for 45 minutes or so and then never again appeared on the bridge of a starship or in the desert landscape of Vasquez Rocks.

Who is eligible for this tournament?  Any character who appeared in one (1) and only one (1) episode of any Star Trek television series.  This includes: The Original Series, The Animated Series, The Next Generation, Deep Space 9, Voyager, Enterprise, Discovery, Short Treks, and Picard.  For our purposes, we’ll consider two-part episodes (eg, “The Best of Both Worlds”) to count as a single episode.  Any character that appears in either or both parts of a two-parter is eligible, so long as they don’t show up in any other episode.  Remember, it’s the character we’re talking about, not the actor.  A one-off character played by an actor who made multiple guest appearances is totally fine.

Who is not eligible for this tournament?  Everyone else.  The main cast of any show is obviously not eligible, nor is any recurring role.  A character who originated in one series and later made an appearance on another also doesn’t count, even if re-cast.  Characters who appear only in the Star Trek feature films do not count.  This is admittedly arbitrary, but I think there’s enough to sift through if we limit ourselves to just the TV series.

What should you do?  Nominate your favorite special guest stars, walk-on cameos, and aliens of the week in the comments below! Please try to include the character’s name, the episode they appear in, and a brief description if you feel it’s warranted.  Memory Alpha is a great resource! Nominations will be seeded by number of upvotes into (hopefully) a 64-item bracket.