Star Trek used to be exploring strange new worlds, but at some point it turned into a never-ending parade of terrible holographic trifles. Here are the ten absolute worst.

It was surprisingly hard to pick the worst Trek holodeck stories, with so many stinkers (and so few good ones) to choose from. It was especially hard not to make the entire list consist of Voyager. As commenter Evlsushi says, "Mentioning a bad Voyager holodeck episode is like shooting really fat, slow fish in a barrel." But here's what we came up with, in rough chronological order:

TNG: 11001001. You could argue this isn't really a holodeck adventure, because Riker doesn't really get "trapped" on the holodeck. But my. God. We, the viewers, are trapped inside Riker's holodeck romance with Minuet, his ideal woman, who's a simpering idiot. She's been created by the Bynars, a race of autistic savants who speak in binary code to each other, and they're about ten million times sexier than she is.
Worst moment: Riker offers to show Minuet his "bone." In a similar vein, I almost included "Outrageous Okona," the "holographic Joe Piscopo" episode, but decided it didn't have enough holodeck awfulness mixed in with the Okona outrageousness.

TNG: Hollow Pursuits. Oh man. Some people really love this episode, in which Lt. Barclay gets addicted to the holodeck, and our heroes have to wean him off it. But I never liked Reg Barclay as a character, and whatever goodness there might have been in the concept of holodeck addiction gets lost in his whining and posturing. Plus TNG can never resist a chance to have its stars dress up in silly outfits and act campy and out of character, so Troi, Worf, Data and the others all wear old-timey garb and act ridiculous.
Worst moment: Troi: "I am the goddess of love and compassion."

TNG: Ship In A Bottle. I'm willing to give the "Dixon Hill" episode a pass, since it won an award in spite of extreme silliness. I'm even willing to let the first Moriarty episode slide, despite its Wishbone-esque quality. But the sequel, where Moriarty takes over the ship, is just a bit too over the top. Especially once he decides he'll be too lonesome as a holographic character wandering the universe alone, and gets his Countess. Also, Moriarty is too easily fooled by the same trick he pulls on Picard and company: making them think they've left the Holodeck when they're still really in there.
Worst moment: Moriarty explains to Picard how much he loves his Countess.

TNG: A Fistful Of Datas. I've already hated on this episode, but it can always stand more hate. Data's mustaches, alone deserve an epic poem in their honor, with heroic couplets and at least 100 stanzas. Plus any father-son bonding between Worf and Alexander is reason enough to hate an episode, and Trek should have learned its lesson about cowboy episodes with "Spectre Of The Gun."
Worst moment: Data in a dress, macking on Worf.

DS9: Badda-Bing, Badda-Bang. Some people really loved Vic Fontaine, the holographic singer who guest starred in several episodes of DS9's final couple of seasons. I don't understand those people, and try to avoid them as much as possible. Vic was like a less cool Guinan, except that he sang. A lot. But to be fair, he was mostly used for some good purposes: like finally getting Odo and Kira, those crazy kids, to hook up. And helping Nog deal with his trauma of losing a leg in battle. (I actually really liked the Nog's leg episode.) But inevitably, some bright spark thought: "Why not have Vic star in his own episode? About mobsters and stuff?" And... no. Bad, bad idea. The awesome Cynic's Corner site explains all the ways this episode fails, including lack of actual humor, Sisco singing, and an implausible plot.
Worst moment: We find out that if Vic dies in the program, his program is deleted permanently from the Matrix. Wha?

Voyager: The Thaw. Yes, I'm skipping over the episodes about the Doctor's holographic family and Ensign Kim's Beowulf simulation. They're pretty hideous, but not in the same league as the worst Voyager holodeck eps. "The Thaw," on the other hand... ugh. There's a clown, okay? And his name is "Fear." And Fear has a bunch of random people, plus the always-feckless Harry Kim, trapped in his virtual world because their bodies are plugged in. Fear the Clown amuses himself by playing silly games and turning Kim into a baby and an old guy. Finally, Janeway instills fear into Fear.
Worst moment: God, where do we start? I guess the Harry Kim baby thing. I dunno.

Voyager: The Killing Game. Aliens trap the Voyager crew in a holographic simulation where they think they're really their holo-characters, and then somehow the aliens are Nazis. It's Springtime for Hitler on the Holodeck. Ugh Ugh Ugh. Although Klingons versus Nazis is kind of great.
Worst moment: One of the Hirogen decides to embrace Nazism as a life philosophy, for real.

Voyager: Fair Haven. Janeway falls in love with a holo-stud in the cheesy "Irish village" holodeck program, and heartstring-tugging romance ensues. Along with ethical dilemmas, as Janeway starts "editing" her beau to make him more suitable (and to delete his inconvenient spouse.) And then she has sex with him — while other Voyager crew members are visiting the holodeck, which, after all, is only one tiny room.
Worst moment: So many. No, wait. how about when Harry Kim questions an order that could save Voyager from imminent destruction, because it might damage the Irish village simulation??

Voyager: Spirit Folk. As bad as "Fair Haven" is, I actually think the sequel episode is worse. The simple Irish folk develop a new and exciting malfunction, so they become aware of the Voyager crew editing reality around them. They decide to burn Harry, Tom and the Doctor as witches, or something.
Worst moment: The villagers hypnotize the Doctor.

Enterprise: These Are The Voyages... You could write a whole essay about how terrible this episode was — and I'm sure tons of people already have. It's as if Berman and Braga wanted to end their version of the Trek franchise with an episode that's not only horrendous, it also makes a strong argument that Trek deserves to die, by giving us some of the series' worst tropes, in one tiny capsule. An unaccountably worse-for-wear Riker and Troi decide, during TNG season 6, to visit a holodeck simulation of one of Captain Archer's missions.
Worst moment: Probably Trip's ridiculous death, although that's not technically a holodeck issue.