1 All the Emperors between Romulus Augustulus and Charlemagne reigned at Constantinople.
2 Capitals distinguish the most eminent Popes and Emperors.
3 Two names bracketed together indicate rival claimants.
4 Those in brackets never received the Imperial crown.
5 This Pope skipped No. XX.
6 From 1438 to 1806, with the exception of Francis I of Lorraine, the House of Hapsburg was on the Imperial throne.
7 Ferdinand and his successors took the title Emperor Elect.
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