A person (or institution) to whom legal title to property is entrusted to use for another's benefit(noun)
WordNet. Princeton University. 2010.
Use "legal guardian" in a sentence
"One of Mamaw’s neighbors is the assigned legal guardian of the dogs, and she takes them away primly when she notes how little Claire and Eve care for them."
"He was going to communicate to Mr. Brithwood of the Mythe, Ursula's legal guardian and trustee, the fact that she had promised him her hand – him, John Halifax, the tanner."