Praenomen

Julius Caesar's praenomen was Gaius.

The Romans evolved a quite different system of nomenclature, which in its classical form consisted of three names, the praenomen (e.g. Marcus), nomen (e.g. Tullius), and cognomen (e.g. Cicero), and two other designations (the name of the father and of the tribe): […]

Tutankhamun's praenomen or throne name was Nebkheperrure, "Lord of the forms of Ra".

The old explanation was that the Greeks applied the name [λαβύρινθος (labúrinthos)] to it [the Temple of Hawara] because the prenomen or "throne-name" of its builder, Amenemhat III., would have been pronounced *Nemarîᵉ, and, by a usual interchange of n with l, transliterated into Greek as Labaris or Lamaris.

In the name Tyrannosaurus rex, "Tyrannosaurus" is the praenomen.