Who was a person who stands for a young or sick ruler?

A notable person who stands for a young or sick ruler is a regent. A regent governs on behalf of a monarch who is unable to rule due to youth, illness, or absence. Historical examples include the Duke of Regency in England who acted for King Henry VI during his periods of incapacity and Queen Regent Maria de’ Medici, who ruled for her son Louis XIII of France while he was still a minor. Regents often wield significant power until the rightful ruler can assume their responsibilities.