Gliese 12 is a cool M-dwarf (about 0.26 solar masses, 3,328 K, 0.27 solar radii), 12.2 light-years from Earth. Gliese 12 b is a 0.9-Earth-mass planet, with an orbital period of 12.8 days, on an eccentric orbit (e ≈ 0.24), discovered in 2024 via transit. The planet was found when it crossed the face of its star, producing periodic dips in brightness that reveal its size and orbital period to space-based photometry. The planet's marked eccentricity suggests past scattering events or perturbations from unseen companions.