KELT-6 is a Sun-like F-type star (about 1.13 solar masses, 6,272 K, 1.53 solar radii), 241 light-years from Earth. KELT-6 c is a 3.71-Jupiter-mass companion, with an orbital period of 3.49 years, at 2.390 AU from its star, on an eccentric orbit (e ≈ 0.21), discovered in 2015 via radial velocity. KELT-6 b is a 0.52-Jupiter-mass companion, with an orbital period of 7.8 days, on an eccentric orbit (e ≈ 0.22), discovered in 2014 via transit. Mutual gravitational tugs between the planets can slowly reshape their orbits, preserving clues to the system's assembly.