Sagittarius A*
Sagittarius A*, the 4.28-million-solar-mass black hole at the center of the Milky Way, and twelve S-stars — including S2, S55, and S38 — on orbits from Gillessen et al. (2017), started at S2's 2018 pericenter passage.
Scenarios
Black Holes
Black holes at the true Schwarzschild scale, each with the star or stars bound to it. Sagittarius A* and the S-star cluster, the X-ray binaries, and the Gaia dormant black holes. Orbits use published periods and masses. Where a mass has not been measured, the description says so.
GU Muscae
GU Muscae (GRS 1124−683): a black hole of about 5.7 solar masses and a K dwarf on a 10.4-hour orbit.
IL Lupi
IL Lupi (4U 1543−475): a black hole of about 9.4 solar masses and an A2 dwarf on a 1.12-day orbit.
SS 433
SS 433: a microquasar with a 13.1-day orbit, drawn with an 8-solar-mass black hole and an A supergiant.
V1033 Scorpii
V1033 Scorpii (GRO J1655−40): a 6-solar-mass black hole and an F subgiant on a 2.62-day orbit.
V1487 Aquilae
V1487 Aquilae (GRS 1915+105): a 10.1-solar-mass black hole and a K giant on a 33.8-day orbit.
V4641 Sagittarii
V4641 Sagittarii (XTE J1819−254): a 6.4-solar-mass black hole and a B giant on a 2.82-day orbit.
Cygnus X-1
Cygnus X-1: a 21.2-solar-mass black hole and the O supergiant HDE 226868 on a 5.6-day orbit.
Cygnus X-3
Cygnus X-3: a Wolf–Rayet star and a compact object, drawn here as a 5-solar-mass black hole, on a 4.8-hour orbit.
Gaia BH1
Gaia BH1: a 9.27-solar-mass dormant black hole and a Sun-like star on a 185-day eccentric orbit.
Gaia BH2
Gaia BH2: an 8.9-solar-mass black hole and a red giant on a 1,277-day eccentric orbit.
Gaia BH3
Gaia BH3: a 32.7-solar-mass black hole, the heaviest known stellar black hole in the Milky Way, and a metal-poor giant on an 11.6-year orbit.
KV Ursae Majoris
KV Ursae Majoris (XTE J1118+480): a 7.5-solar-mass black hole and an M dwarf on a 4.08-hour orbit.
LMC X-1
LMC X-1: a 10.9-solar-mass black hole and a 32-solar-mass O star on a 3.91-day orbit, in the Large Magellanic Cloud.
M33 X-7
M33 X-7: a 15.7-solar-mass black hole and a 70-solar-mass O star on a 3.45-day eclipsing orbit, in the Triangulum Galaxy.
Omega Centauri BH-2
oMEGACat BH-2: a 4.46-solar-mass black hole and a turnoff star on a 94-year eccentric orbit in Omega Centauri.
QZ Vulpeculae
QZ Vulpeculae (GS 2000+25): a black hole of about 7.2 solar masses and a K dwarf on an 8.3-hour orbit.
V Puppis
V Puppis: a candidate black hole of at least 10.4 solar masses orbiting a B-star eclipsing binary every 5.47 years.