I know Charlemagne, Alfred the great and Constantine are some of the members of a symbolic small order of leaders who each embody fundamental principals of virtue and chivalry. In this group there is about 5-10 of them (I can't remember the exact number) and their effigies appear on religious sites around Europe such as statues on cathedrals. If anyone knows the name of the collective for them it would be much appreciated.
You might be thinking of the Nine worthies, nine kings which personified the chivalric virtues. They were:
- Alexander the Great
- Julius Caesar
- Judas Maccabeus
- King Arthur
- Godfrey of Bouillon
Note that in the group there were three pagans, three Jews and three Christians.
However, the Nine worthies were not explicitly used in church imagery, AFAIK, but can be found on civic buildings like the City Hall in Cologne.