Star Trek's Voyager and Enterprise never had a true crossover

Star Trek: Voyager and Star Trek: Enterprise had a lot in common. They both were flagship shows for the fledgling UPN channel, they both featured the first of their types of captains (the first female, the first big-budget hire) and they both existed on the furthest ends of the Trek timeline. At least at the time.

When Enterprise began and Voyager ended, the two shows represented the earliest and the latest moments in the show's timeline. Enterprise was the show that started the Federation, while Voyager went deeper into space than anyone else ever could have. They were both fantastic series and had a lot in common.

The one thing they didn't have in common, however, was each other. Despite Deep Space Nine and The Next Generation crossing over with Voyager, and The Next Generation crossing over with Enterprise, Voyager and Enterprise never did one with another.

Rather shocking, considering they were on the same network one after another. There were a few call-backs (or call-forwards?) to Voyager and other series, during Enterpise's run, however. For instance, the Borg that was defeated on the outer hull of the Enterprise-E during First Contact appeared in an episode of Enterprise, while a callback to a popular Voyager holodeck, The Bride of Chaotica, was seen as a throw-away gag in an episode of Enterprise.

Aside from that, however, the two shows never did a formal crossover, despite what some claim. It may be the least cross-covered show in franchise history. No other show was as limited in its crossovers as Enterprise.

Even the Original Series got to flex itself after the fact. Spock, Leonard McCoy, and Montgomery Scott were in various episodes of The Next Generation, with McCoy (Good 'ol Bones), showing up in the pilot. Later, Pavel Chekov and James T. Kirk himself would appear in the TNG film, Star Trek Generations.

Deep Space Nine crossed over with a lot of shows, from The Next Generation to Voyager (Quark in Voyager's pilot) and even The Original Series.

The newer shows are even more so, with Discovery leading to Strange New Worlds as a direct spinoff and then later crossing over with Lower Decks. Prodigy has also done a good job of bringing in other shows into their universe, as well as Lower Decks.

Only Enterprise was limited to how and how they did crossovers. There were rumors that William Shatner was set to reprise his role as James Kirk in season five, but as the show was canceled, that never ended up happening.