“Star Trek: Deep Space Nine” (DS9) and “Star Trek: The Next Generation” (TNG) are two cornerstones of the Star Trek franchise, and over the years, they’ve had a number of crossovers that delighted fans. Here, we rank these memorable moments from worst to best:

1. Best Overall Crossover: “The Maquis” Parts I & II (DS9 Season 2, Episodes 20 &21)

These episodes set up key conflicts that would continue throughout both “Deep Space Nine” and “The Next Generation”. The complex storyline involving Starfleet officers joining the Maquis sparks immense inter-series drama and compels viewers to engage with the broader political landscape of Star Trek’s universe.

Ranking these crossovers offers just a glimpse into how interwoven these two series are within the Star Trek canon. Each crossover adds layers of depth and enjoyment for fans who have invested time in both beloved series.

2. The Pilot: “Emissary” (DS9 Season 1, Episode 1 & 2)

The two-part pilot of DS9 naturally crosses over with TNG since it directly follows Chief O’Brien’s transition from the Enterprise to Deep Space Nine. Picard also makes an appearance that addresses his assimilation by the Borg and its aftermath — critical for both his character development and Sisko’s backstory.

3. Best Appearances: Various TNG Characters on DS9

DS9 featured several guest appearances from TNG cast members such as Q and Vash in “Q-Less” (Season 1, Episode 7), and several more throughout the series. These provided important narrative continuity between the shows and offered additional layers to already well-loved characters.

4. “Defiant” (DS9 Season 3, Episode 9)

In this gripping episode, Jonathan Frakes reprises his role as Thomas Riker, Will Riker’s transporter clone. The crossover bridges TNG and DS9 cleverly by integrating a TNG character’s personal story with the political intrigue of DS9.

5. “Phantasms” (TNG Season 7, Episode 6)

This episode features a brief but enjoyable cameo by DS9’s Leeta (played by Chase Masterson), who appears as an image in Data’s dream sequence. Although it does little to forward any crossover narrative, it is an amusing Easter egg for dedicated fans.

6. “Firstborn” (TNG Season 7, Episode 21)

A minor crossover where Quark makes a brief appearance on TNG. Quark tries to sell artifacts to Worf for Alexander’s Age of Ascension ceremony. It’s a fun nod but ultimately forgettable in the grander scheme of both series.

7. Worst: “Birthright, Part I” (TNG Season 6, Episode 16)

In this crossover, Worf discovers survivors from the Khitomer massacre, but the episode primarily serves as a setup for a “DS9” storyline. While it’s vital to Worf’s personal story, the crossover element feels forced, and the DS9 characters do not get enough screen time to create a substantial impact.