i think wolfenstein3d was the first fps...
Theres whas a few FPS before Wolf3D (thres even a FPS pacman for Commodore64), but Wolf3D got it right (with textured walls) and fast gameplay (lots of monsters to kill). And of course, most people only know Wolf3D, except morons that think that the first is CounterStrike... or really shit that move that think the first FPS is Halo2.
1984, Supersoft 3D Glooper.

( the image looks graphic, but is actually ascii draw)

More 3d games
speaking of old games who remembers alex the kid!?? the japanese sushi boy who now eats burgers!??
and the third person idea is great but no
its not worth the trouble and the 'spectators' are just units e.g. just another model like th humans and aliens just no body to shoot at and gravity is set to zero for them. if you actually think about it you really ARE a 'spectator'