Yes. The Kuiper belt is full of massive, yet-to-be-documented asteroids, planetoids, comets, and dwarf planets.

But then with the Kuiper Belt and the Oort Cloud you're getting into interstellar space, yes ? As space-based telescopes improve by another order of magnitude or two (one hopes), will we need a new term for drifting objects gravitationally influenced both by our Sol and by (say) the Centauris ?

Speaking of which, TIL there's been more discovered in those systems. There's Alpha Centauri A B & C (C is a.k.a. Proxima Centauri) AND Beta Centauri A B & C. You can't tell your players without a scorecard.