HD 187123 is a Sun-like G-type star (about 1.04 solar masses, 5,790 K, 1.15 solar radii), 46.0 light-years from Earth. HD 187123 b is a 0.52-Jupiter-mass companion, with an orbital period of 3.1 days, at 0.043 AU from its star, discovered in 1998 via radial velocity. HD 187123 c is a 1.99-Jupiter-mass companion, with an orbital period of 10.4 years, at 4.890 AU from its star, on an eccentric orbit (e ≈ 0.25), discovered in 2008 via radial velocity. Mutual gravitational tugs between the planets can slowly reshape their orbits, preserving clues to the system's assembly.