HAT-P-18 is an orange K-type dwarf (about 0.77 solar masses, 4,803 K, 0.75 solar radii), 161 light-years from Earth. HAT-P-18 b is a 0.20-Jupiter-mass companion, with an orbital period of 5.5 days, at 0.056 AU from its star, and an equilibrium temperature near 852 K, on an eccentric orbit (e ≈ 0.08), discovered in 2010 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. HAT-P-18 b orbits well inside Earth's distance from the Sun.