Regius

Regius may refer to:


 * Regius Professor, "Royal" Professorships at the universities of Oxford, Cambridge, St Andrews, Glasgow, Aberdeen, Edinburgh and Dublin
 * Regius Keeper of the Royal Botanical Garden Edinburgh
 * Raphael Regius (c.1440–1520), Venetian humanist
 * Henricus Regius (1598–1679), Dutch philosopher and physician
 * Codex Regius, Icelandic manuscript in which the Poetic Edda is preserved
 * Hippo Regius, ancient name of the modern city of Annaba, Algeria
 * Titulus Regius, 1483 statute of the Parliament of England, giving the title "King of England" to Richard III
 * Animal names:
 * Argyrosomus regius, Meagre, Shade-fish, Salmon-Basse or Stone Bass
 * Hylodes regius, frog of Brazil
 * Phidippus regius, Regal Jumping Spider
 * Philautus regius, frog of Sri Lanka
 * Pseudorhabdosynochus regius, a Monogenean
 * Python regius, python