who are these rulers mentioned last?
It  is a person appointed to govern a state "pro tempore" because the regnant monarch is a minor, is absent, abdicated the throne, is incapacitated or dead, or inability to discharge the powers and duties of the monarchy.
Regent
A regent (from the Latin : ruling, governing) is a person appointed to govern a state "pro tempore" (Latin: 'for the time being') because the regnant monarch is a minor, is absent, abdicated the throne, is incapacitated or dead, or inability to discharge the powers and duties of the monarchy. 
how old was the queen of scots when she died 44 years old ( 1542-1587). who is this queen? The Queen of Scots. which country did she rule? Scotland. how did she spend her childhood? She spent most of her childhood in France while Scotland was ruled by regents.
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Regent [SEP] Introduction
A regent (from the Latin : ruling, governing) is a person appointed to govern a state "pro tempore" (Latin: 'for the time being') because the regnant monarch is a minor, is absent, abdicated the throne, is incapacitated or dead, or inability to discharge the powers and duties of the monarchy. The rule of a regent or regents is called a regency. A regent or regency council may be formed "ad hoc" or in accordance with a constitutional rule. "Regent" is sometimes a formal title granted to a monarch's most trusted advisor or personal assistant. If the regent is holding his position due to his position in the line of succession, the compound term "prince regent" is often used; if the regent of a minor is his mother, she is often referred to as "queen regent" or "empress dowager".