Encounter at Farpoint
A new beginning: The pilot episode of TNG, naturally, established a plethora of firsts: the first time we see the holodeck, saucer separation, Q, etc. But perhaps the most significant benchmark this episode represents is the first time in Star Trek that we see a captain and his ship at the beginning of their mission. When the Original Series premiered, it simply jumped us right into the middle of the Enterprise's five-year mission. By the 1980's, the trend in television was to use the pilot episode of a series to depict the show's premise being set into motion and to show the characters coming together for the first time. To its benefit, TNG followed this trend, and the formula continued with all subsequent Star Trek series.

The Last Outpost
First appearance of Ferengi: Early in the run of TNG, Gene Roddenberry and company wanted to introduce a "new alien threat" that would rival the Klingons from the Original Series generation. The debut of the Ferengi may not have lived up to this expectation, but it did lay the foundation for the exploration of a set of ethics unique in the Star Trek universe. Ferengi culture provided another viewpoint on what's important in life, which subsequent writers used to great advantage to create clashes of values that spoke as much to the human condition as any other conflict. This was done mostly through the character of Deep Space Nine's Quark, played by Armin Shimerman, who started his big-lobed Star Trek career in this very episode.

Where No One Has Gone Before
The farthest any starship has travelled: The original Enterprise was on its way to the Andromeda galaxy, but it only got part of the way there. The Enterprise-D must have the distinction of being the first and only Federation starship to actually visit a different galaxy. And it didn't stop there. Thanks to the Traveler, Picard's crew traversed over a billion light-years, all the way to Galaxy M33 and beyond, into the unfathomable unknown where thoughts are indistinguishable from material objects. Truly where none have gone before.

Heart of Glory
First exploration into Klingon culture: This was the first episode that truly got under the skin of Worf and explored some of the cultural values and beliefs of his people. Klingons in the Original Series were seen as dishonorable, but in TNG starting with this episode, we get a different angle: a warrior race who values honor above all else. Of course, like most conscious beings, they don't always live up to their own code of ethics, but that's part of the complexity of a culture that is probably the richest one ever explored in the Star Trek universe. The "death howl" is just one aspect of this culture that is introduced in this episode and revisited several times in subsequent shows.

Skin of Evil
First (permanent) death of a principal character: In Star Trek we had never lost a beloved main character before (if you don't count Spock, who didn't stay dead) —it was always the infamous "redshirts" who got themselves killed on away missions. But for the first time the dangers of facing down an enemy on an alien planet befell one of the major players. Of course, it happened because a principal cast member wanted to leave the show, so the writers arranged for Tasha Yar, played by Denise Crosby, to fall victim to the rageful Armus. And despite the most desperate attempts ever seen in Star Trek to save a life, hers was lost. (Of course, Yar managed to stay alive in an alternate timeline, but that's another story ... )

The Measure of a Man
The legal rights of artificial beings first put to the test: One of the most intellectually challenging episodes ever written for Star Trek dealt with the legal status of an artificial lifeform, in this case an android. Does Data have the right to determine his own destiny? Is he property or person? This fascinating examination into the nature of sentience laid the groundwork for further discussion of the topic, such as later in TNG with the Exocomps, and in Voyager regarding holograms. And no doubt it'll become an issue in real life in the not-too-distant future.

Q Who?
First encounter with the Borg: They were more threatening than the Klingons and more menacing than the Conspiracy parasites. Arguably the most formidable and evil force in the galaxy, the Borg were introduced to the Federation when Q hurled the Enterprise-D thousands of light-years away, out of spite for not being allowed to join the crew. Q would later argue that the encounter was inevitable, but his little stunt served to give the lowly humans advance warning of what was to come. And indeed, this first contact would pave the way for some of the most brutal conflicts to ever take place in space.

Family
First full episode devoted to the aftermath of a previous episode: After Picard's abduction by the Borg and the skirmish that ensued, the Enterprise-D crew got to go home to recuperate. Star Trek characters had faced many intense situations with tremendous stakes, but never before had the emotional and psychological consequences of such incidents been explored so thoroughly. This episode, perhaps more than any other in Star Trek, puts a human face on our heroes as they try to come to grips with the awful things that have just happened. We even get to see Picard cry. Who wouldn't?

Ensign Ro
Introduction of Bajorans: Many new species were introduced in TNG, but few have had as much of an impact on Star Trek history as the Bajorans. Their plight as a people oppressed for decades by the Cardassians and their subsequent liberation formed the basis of the entire premise for Deep Space Nine, and impacted Voyager as well. And—with the possible exception of the Klingons—no alien race in the Trek universe has provided as intricate a look into how a culture's religion and internal politics affect their dealings with outsiders. And it all started when Ensign Ro was assigned to serve on the Enterprise-D.

The First Duty
First look at Starfleet Academy: We've heard about Starfleet Academy since the beginning of the Original Series, but we never actually got to see it until this 5th-season TNG episode, when Picard gets invited to give a commencement speech. His visit is tarnished by tragedy, however, and the drama that ensues allows us an in-depth look at the experience of being a Starfleet cadet. Here we also get to finally see the irascible Boothby, the beloved groundskeeper played by the late Ray Walston, whom Picard had previously described to Wesley as one of the wisest men he ever knew.

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