GTS Celebrity Constellation (formerly Constellation) is a Millennium-class cruise ship operated by Celebrity Cruises, a subsidiary of Royal Caribbean Group. She was renamed in May 2007 to add the "Celebrity" prefix, joining her three sister ships: Celebrity Infinity, Celebrity Summit, and Celebrity Millennium.

She was built at the Chantiers de l'Atlantique shipyard in St. Nazaire, France. The ship is powered by a COGES power plant of gas turbines and a steam turbine providing up to 60 megawatts for the electric systems and two 19 MW Rolls-Royce/Alstom MerMaid azimuth thrusters for propulsion. In 2007, an additional diesel engine was fitted as a fuel-saving measure. The ship can run on any combination of the gas turbines or diesel. In port, she generates electrical power from the diesel.

During the summer period the ship sails to the Mediterranean, repositioning to the Caribbean in the winter months.

Celebrity Constellation was scheduled to complete an extensive renovation in May 2020. However, as a result of the business impact from the Covid-19 pandemic, these plans are delayed until a future unannounced date. Another rumor that Celebrity Constellation and sister ship Celebrity Infinity are to be sold or leased to Spanish cruise line, Pulmantur, has been denied by Celebrity Cruises.

In mid-2021, Celebrity Constellation received a multi-million dollar refit.