Here are some series I have loved in Season 1 or 2 that have died an early death, in approximate reverse order. These are all series where I became a fan within the first two seasons in real time and was religious about not missing an episode.
The Agency (CIA show with Jason O’Mara and Paige Turco), brilliant in Season 2, never on DVD. 🙁
The Lone Gunman
Space: Above and Beyond
oh, and Twin Peaks
Notice anything about the show longevity?