TOI-6420 is a Sun-like F-type star (about 1.17 solar masses, 6,020 K, 1.31 solar radii), 635 light-years from Earth. TOI-6420 b is a 8.20-Jupiter-mass companion, with an orbital period of 7.0 days, at 0.075 AU from its star, and an equilibrium temperature near 1,213 K, on an eccentric orbit (e ≈ 0.08), discovered in 2025 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.