9. Being A Hologram
At times, the show was mercilessly cruel to Chris Barrie as the ship's hologram. The jokes are brilliant and "Hadron Head" might be the greatest insult of all time, but the novels really go into fine detail when explaining what it's like to be a hologram.
Originally, the holograms were greyscale versions of their namesake and, quite often, less observant members of the crew would walk straight through them as though they were ghosts.
Worse still, in instances of low power, they become borderline transparent and can see through their own eyelids, preventing sleep, and worst of all they cannot touch or really function as a human at all.
There are a few upsides to being made entirely of light and never ageing, as you continue to experience life after your body has given out, but there really are too few to outweigh the crushing day-to-day reminders that you aren't actually the person you think you are.
Instead, you're simply a manifestation of their appearance and personality based on observations from the ship's security footage.
Life after death is one thing, but being a hologram is just death after death.