12. Star Trek: Insurrection (1998)
Coming off the back of the excellent First Contact, Paramount decided they wanted a lighter tone, seeking to make the "sexiest and funniest" Star Trek film more in the vein of The Voyage Home than First Contact's bleaker vision.
As a result, they replaced Ronald D Moore and Brannon Braga with Deep Space Nine writer Michael Piller and charged him with making Star Trek: Stardust (thank GOD that name didn't make it through). Incorporating elements of Heart Of Darkness, the elemental story of the Fountain Of Youth and a sort of Morlock/Eloi friction between two apparently separate alien races.
Jonathan Frakes directed, and despite several stages of development and changes to the script, it's simply not very entertaining. There are some reasonably diverting ideas (like Geordi LaForge getting his eye-sight back and Data's rogue status) but the tone is too fluffy and idealistic. And while that's always been a part of Star Trek, to have it come after First Contact and with Voyager and Deep Space Nine both vying for Trekker attention it just wasn't substantial enough.