So TNG has offered a surfeit of "baddies" over the seasons. Which are your contenders for favorites? Not as much per story per se, but concept and execution for which there can be many. In no order, for each:
Season 1:
Season 2:
Season 3 (...so many...) :
Season 4:
Season 5:
Season 6:
Season 7:
Season 1:
- The Edo god. Not evil as such and it's clear it had sentience and reason
- Armus. Evil of the best sort, and will even kill indiscriminately - a rarity in shows. Tasha's death is often poohpoohed, but I'd argue it's misunderstood because evil will kill. Given how uneven Tasha was written in the show, her death arguably has a double-meaning, one meta one in-story
- Bynars. Again, not evil, just desperate, and they created a near-perfect evil in Minuet.
- The insect crawdads. "Conspiracy" is a curate's egg of a story as it feels so unlike TNG yet feels so like TNG, an obvious missed opportunity to do a sequel (are they related the original Borg from season 2?)
- Lore (and the Silicon entity). The plotting is dumb but the villains are magnificent
Season 2:
- Nagilum. Another world's amoral scientist lends to a great story as we are an vicarious extension of the crew.
- Moriarty. The computer can create the means to destroy the ship without realizing it and with such panache. Fill me with crumpets too!
- The sentient being behind the vortex. "Time Squared" is an interesting story as there's no cohesive villain, only a presence Troi senses. Could Q be shielding himself? Is this another entity? It's wonderfully open-ended.
- Borg. Intended as an insect species, possibly inspired from Battlestar Galactica, the writers' strike and budget issues retooled them as a much more interesting foe (despite being a plain gestalt!)
Season 3 (...so many...) :
- The Shelliak - a very inventive and creative, conceptually alien design well-realized
- Menthars - no, they're not an ingredient in ciggies, they are cunning and created a neat death trap based on a principle Newton would discover centuries later (different species and planets, relative times of development, all rolled into a neat story.)
- Romulans. Nice to see them back fully, complete with arc.
- Yuta. The basic idea behind "That Which Survives" was remade cleverly for this episode she's in.
- Borg. Obviously
- Cmdr Shelby - she's out for Riker's job, in "Staaaaaaaar Trek, the soap opera generation!" Still a great episode, but one has got to chuckle at times.
Season 4:
- Wesley, albeit by accident. Traps his mommy in a warp bubble and thankfully creepy Traveler was watching.
- Romulans. More intrigue!
- Ardra - hilariously evil
- Krola - who really isn't a baddie, just xenophobic, but "First Contact" is loaded with a plethora of invigorating characters written as people and not popsicle sticks
Season 5:
- Tom Paris Ycarno :P - gets Wesley to do the 24th century equivalent of smoking in this not-a-very-special-episode/PSA
- Ktarians - anyone who can just about topple the whole of the Federation due to Riker's jiggy is worth a mention
- Romulans, apart from some cartoon antics early on, become proper scheming later on in the season
Season 6:
- Again with the Romulans, as we get a little more insight into their culture but not in a way that wears them out
- Q is back with his amoral omnipotence, twice!
- Cardassians make their most direct display yet and decently so. Imagine if Picard had broken down and living the life Muldred said, with Captain Riker forevermore
- Rogue technicians. Nice to see how bands of rogues can still exist in Federation planets, though few must exist. At least it's not the usual overdone cliché of "evil captain of the week, again". Plus, it all allows Picard to be an action hero but in a convincing way
Season 7:
- The Q - the lot of them now want humanity erased, in a way that lets Picard be the cause of humanity's demise, with our Q actually defending it in a quaint turn of events
- Interphasic critters interfering with Data. "Phantasms" is one of season 7's underrated gems
- Romulans, again, with Admiral Pressman. The Pegasus is right out of TOS philosophy, only it's with the evil admiral o' the week trope but done compellingly so
- Parallel universes. Can't we just have the one? Not a baddie as such, but makes for an occasionally great storyline. Just don't treknobabble time travel to have everyone say none of it ever happened at the end, in-story rules being followed helps immensely.
- Dr Crusher. The script having her cite some T-Cell treknobabble nearly caused novelty deaths of all the crew and the ship. Even Dr Pulaski wouldn't be so fast and loose. What happened to the Dr Crusher who said "real research takes time"? There was nothing so significant with Barclay's hypochondria (or 1-in-1000 and slight cell mutation) that he needed a hypospray to become a hyper arachnid with so fast... but thanks to her, now something urgent WAS needed! All that said, Gates McFadden directed a creative yet iffy script to terrific heights, making it so readily rewatchable and (creepy for all the right reasons). Shame she didn't do more directing as she's flipping awesome. Imagine if she did "Phantasms" and other high-concept psychological thriller-style episodes...