Looking for shows or movies with simular (ish) concept

Friendships, advantages and disadvantages of being a spirit (something else), or just having to cope with something that no one else can see.
Just look at my list and feel free to add to it. All suggestions (with good actors/characters preferably) will be appreciated.

Ghosts:
Bob/Hroberth of Bainbridge - Dresden Files
Marty Hopkirk - Randall & Hopkirk (Deceased)
Sam Wheat - Ghost
Spike - Angel (S05) - Haven't seen it yet, but this will be LEGEN ...wait for it... DARY!!!

Holograms:
Arnold J. Rimmer - Red Dwarf
Emergency Medical Hologram - Star Trek: Voyager
Al Calavicci - Quatum Leap


In The Mind:
Harvey (neural clone of Scorpius) - Farscape
Lashiel - Dresden Files (book verse & not so favorite, just a good example)