Right now, Arri-PL is by far the most common 24 x 36 mm frame-capable cinematography-only mount, with EF the strongest option in the 24 x 36 mm shared cinema-stills mounts category. In theory, Arri-PL ought to be adaptable to EF and Nikon F mounts, because the mount-to-sensor distance of the Arri PL is 8 and 6 mm deeper than that of EF and F mounts respectively. Panavision has its own 24 x 36 capable mount PV for its own brand lenses and cameras. For 16mm frame, C mount. For 8 mm frame, D mount. For ridiculously expensive and fabulous 70mm frame, Arri MaxiPL.
I know nothing about cinematography lens adapters. I do stick Nikon F and M42x1 screw mount lenses on my Canon 6D occasionally. Mostly a trip down memory lane, except for the AIS Nikkor 50 f/1.2, which, stopped down, is a darn good lens, and has funky aberration (feature - interesting look) characteristic of double gauss design fast lenses at wide open, and the AIS Nikkor 105 f/2.5, which isn't as sharp as some modern lenses, but renders very nicely.
shadowblade, you have endoscopes just lying around? BTW, the latest endoscopes really do have pretty good optics, dramatically better than those of 20 years ago. The image circle must be very tiny, enough for an 8 mm frame, perhaps.