
Detail of Roman Emperor Constantine I (274–337) in Piero della Francesca’s Vision of Constantine, 1458
Though the name Constantine has never been particularly common in the Anglophone world, it’s long enjoyed great popularity in various other forms in Orthodox Christian countries. It derives from the Latin name Constantinus, which in turn derives from Constans (steadfast, constant).
The name became popular in the Orthodox world because of the above-pictured Constantine the Great (Flavius Valerius Aurelius Constantinus Augustus), who ruled from 306–337. He was the first emperor to stop the persecution of Christians, following his religious conversion.
Some historians, however, believe he privately continued worshipping the Roman deities and only converted to Christianity because it was politically expedient.

King Konstantinos I of Greece, 1868–1923
Other forms of this name include:
1. Konstantin is Russian, Bulgarian, Serbian, Macedonian, Czech, German, Finnish, and Hungarian. Nicknames include Kostya (Russian), Konsta (Finnish), and Kosta (Bulgarian and Macedonian). The variation Konštantín is Slovak.
2. Kostadin is Bulgarian and Macedonian.
3. Kostyantyn is Ukrainian.
4. Konstantine is Georgian.
5. Kostandin is Albanian and Vlach.
6. Konstantinos is Greek. Nicknames include Kostas and Kostis.
7. Kanstantsin is Belarusian.
8. Konstantyn is Polish.
9. Konstanty is also Polish.
10. Konstantinas is Lithuanian. The nickname is Kostas.

Konstantin Päts (1874–1956), first president of Estonia
11. Konstantīns is Latvian.
12. Constantin is Romanian and French. Romanian nicknames include Dinu, Costin, Costel, and Costicǎ. The variation Constantín is Aragonese.
13. Cystennin is Welsh.
14. Costache is a Romanian variation.
15. Costantino is Italian, Spanish, Portuguese, and Galician.
16. Constantijn is Dutch. Nicknames include Stijn, Tijn, and Stan.
17. Considine is Irish.
18. Còiseam is Scottish.
19. Causantín is Pictish.
20. Constantí is Catalan.

Georgian writer Konstantine Gamsakhurdia, 1893–1975
21. Constaintín is Irish.
22. Costantìnu is Sicilian. Without an accent mark, this spelling is also Sardinian.
23. Custantinu is also Sicilian.
24. Kĕştentině is Chuvash.
25. Kuonstantėns is Samogitian, a language spoken in Lithuania.
26. Kostoku is Evenki, a Tungusic language spoken in Russia and China.
27. Kystynchi is Mari, a Uralic language spoken in Russia.
28. Kushchta is Khanty and Mansi, which are also Uralic languages in Russia.
29. Konstandinos is a variant Greek form.
30. Kojadin is a rare Serbian form.

Irish politician and activist Countess Constance Markievicz, 1868–1927
The female name Constance is much more common in the Anglophone world. It’s the Medieval form of the Latin Constantia, and was introduced to England by the Norman occupiers. An early bearer was a daughter of William the Conqueror.
In the U.S., the name was in the Top 100 from 1946–53, with its highest rank to date, #83, in 1949. Its final year in the Top 1000 was 1999, when it was at the very bottom of the chart. Constance is currently much more popular in France, where it was #94 in 2018. In England and Wales in the same year, it was #275.
Other forms of Constance include:
1. Konstancia is Hungarian and Swedish.
2. Konstantina is Georgian.
3. Konstancja is Polish. The variation Kónstancja is Kashubian.
4. Konstanze is German.
5. Konstantze is Basque.
6. Konstancie is Czech. The last two letters are pronounced separately, not as one.
7. Konstanca is Sorbian.
8. Kûnstânse is Greenlandic.
9. Kostanze is Basque.
10. Konstance is Latvian.

Austrian musician Constanze Mozart (née Maria Constanze Cäcilia Josepha Johanna Aloysia Weber), 1762–1842
11. Konstanse is Norwegian and Swedish.
12. Constantine is French.
13. Constanze is German.
14. Constanza is Spanish, Galician, and Italian.
15. Costanza is Italian.
16. Constanţa is Romanian.
17. Constança is Portuguese.
18. Constância is also Portuguese.
19. Konstancija is Serbian, Latvian, Lithuanian, and Croatian.
20. Konstantsiya is Russian.
21. Konstantia is Swedish.