Rigel
Rigel appears to be as a single star, but in fact it's a stellar system of at least four stars. That include Rigel A, Rigel Ba, Rigel Bb and Rigel C. Rigel Ba and Bb orbits around each other every 9.8 days, while Rigel C orbits around Rigel B binary every 63 years. The distance from Rigel A and BC is ~2 200 AU, so the orbital period of each other is ~24 000 years. Rigel Ba, Bb and C have a mass of 3.84; 2.94; and 3.84 solar masses, and therefore they're B-type main sequence stars.