Outside Japan, beginning with Emperor Shōwa, the Emperors are often referred to by their given names, both whilst alive and posthumously.
The current Emperor on the throne is typically referred to by the title Tennō Heika (天皇陛下, "His Majesty the Emperor"), Kinjō Heika (今上陛下, literally "His Current Majesty") or simply Tennō, when speaking Japanese.