In the context of private client, an (adult) individual appointed to take parental responsibility for a child under the age of 18 years.

For further details (including how guardians can be appointed), see Practice note, Appointing guardians in wills.

In the context of family law, a person who has been appointed to care for a child where both parents or a person who holds parental responsibility by virtue of a child arrangements order or special guardianship order have died. This assignment of parental responsibility can happen through a parent's will or by court order (section 5, Children Act 1989).