HATS-66 is a Sun-like F-type star (about 1.41 solar masses, 6,626 K, 1.84 solar radii), 1,478 light-years from Earth. HATS-66 b is a 5.33-Jupiter-mass companion, with an orbital period of 3.1 days, at 0.047 AU from its star, and an equilibrium temperature near 1,998 K, on an eccentric orbit (e ≈ 0.06), discovered in 2018 via transit. The inner world is a hot Jupiter — a gas giant hugging its star at a fraction of Mercury's distance — a class that forced astronomers to rethink how giant planets form and migrate inward.