This character is a godparent.

A godparent, in many denominations of Christianity, is someone who bears witness to a child's baptism, although the term has also been used in a legal sense. In both religious and civil views, a godparent tends to be an individual chosen by the parents to take an interest in the child's upbringing and personal development, and to take care of the child should anything happen to the parents.
In fairy tales, a fairy godmother is a fairy with magical powers who acts as a mentor or parent to someone, in the role that an actual godparent was expected to play in many societies.