|Rhalgr appears to be inspired by the Hindu god Vishnu in a similar manner as the classic recurring Final Fantasy character, Ramuh. Ramuh himself appears to be based on the epic Hindu poem, Ramayana. The main character, Raama, was said to be an incarnation of the god Vishnu, and it's possible Ramuh is a merging of those two names. Ramuh has also gone by the name Indra in early Final Fantasy games. Indra was the Hindu god of rain, lightning, and storms, thus the reason Ramuh is always associated with lightning. Like Rhalgr, Ramuh is often depicted as a magi with a staff.
The phrase "breaker of worlds" used to describe Rhalgr is similar to the famous quotation that Robert Oppenheimer, director of the Manhattan Project, used of the god Vishnu to describe seeing an atomic explosion for the first time: "Vishnu is trying to persuade the Prince that he should do his duty and to impress him takes on his multi-armed form and says, 'Now I am become Death, the destroyer of worlds.'"
Rhalgr's flaming meteor symbol is likely a reference to the ultimate spell of destruction in Final Fantasy VII, Meteor, said to be powerful enough to destroy a planet.