HD 165131 is a Sun-like G-type star (about 1.06 solar masses, 5,870 K), 57.4 light-years from Earth. HD 165131 b is a 18.7-Jupiter-mass companion, with an orbital period of 6.41 years, at 3.540 AU from its star, on an eccentric orbit (e ≈ 0.67), discovered in 2023 via radial velocity. The planet betrayed itself through the star's reflex motion — a technique that first revealed worlds around Sun-like stars in the 1990s and remains a workhorse of exoplanet discovery. The planet's marked eccentricity suggests past scattering events or perturbations from unseen companions.