I actually had problems finding stuff that qualifies as stand-alone. So much is serialized these days...
TOS: none that comes to mind, this is by far my smallest shelf. And it's dusty.
TNG: Dominion War duology by John Vornholt (standalone story, if split over 2 books)
DS9: A Stitch in Time by Andrew Robinson
VGR: Pathways by Jeri Taylor
ENT: A Choice of Futures by Christopher L. Bennett * (I guess this qualifies as standalone until the next one is due)
... and of the novelverse series:
NFR: Once Burned by Peter David
KE: Diplomatic Implausibility, by KRAD
and if any part of Titan can be qualified as standalone: Orion's Hounds, by Christopher again.
I'm reasonably sure SCE and Vanguard don't really qualify for the list, or if TLE does, so I'm leaving it at this.
TOS: none that comes to mind, this is by far my smallest shelf. And it's dusty.
TNG: Dominion War duology by John Vornholt (standalone story, if split over 2 books)
DS9: A Stitch in Time by Andrew Robinson
VGR: Pathways by Jeri Taylor
ENT: A Choice of Futures by Christopher L. Bennett * (I guess this qualifies as standalone until the next one is due)
... and of the novelverse series:
NFR: Once Burned by Peter David
KE: Diplomatic Implausibility, by KRAD
and if any part of Titan can be qualified as standalone: Orion's Hounds, by Christopher again.
I'm reasonably sure SCE and Vanguard don't really qualify for the list, or if TLE does, so I'm leaving it at this.