HAT-P-11 is an orange K-type dwarf (about 0.81 solar masses, 4,653 K), 37.8 light-years from Earth. HAT-P-11 b is an eccentric warm Neptune with detected water vapor, among the smallest planets with a measured transmission spectrum. HAT-P-11 b is a 0.07-Jupiter-mass companion, with an orbital period of 4.9 days, at 0.053 AU from its star, on an eccentric orbit (e ≈ 0.25), discovered in 2010 via transit. HAT-P-11 c is a 2.68-Jupiter-mass companion, with an orbital period of 9.20 years, at 4.100 AU from its star, on an eccentric orbit (e ≈ 0.65), discovered in 2018 via radial velocity. Mutual gravitational tugs between the planets can slowly reshape their orbits, preserving clues to the system's assembly.