Ruby Princess is a Crown-class cruise ship operated by Princess Cruises, a subsidiary of Carnival Corporation & plc. At 113,561 GT, the vessel is the third and last in a series of three ships, known as the Crown class, that was built with design modifications distinguishing them from their older Grand-class sister ships. Delivered in 2008 by Italian shipbuilder Fincantieri, Ruby Princess also became the ninth and final Grand-class ship to join the Princess Cruises fleet.

The Grand class is a class of cruise ships. Ships in the class are operated by the cruise lines Princess Cruises, P&O Cruises and P&O Cruises Australia. The class consists of several series (subclasses) of sister ships, most of which were built by Fincantieri in Monfalcone and Trieste, northern Italy. The first vessel of the original Grand class, Grand Princess, entered service in 1998.