The next morning Harry went to visit his aunt whose name was Lady Aghaten.

[yi-ing]

Can we use "whose for people too? Is there other better substitutions to make sentence sound more natural?

The next morning Harry went to visit his aunt whose name was Lady Aghaten.

He married an actress whose mother died when she was only three years old.

 

[Raymott]

Yes, you use "whose" with people.
You need a comma after 'whose' if the rest is additional information rather than part of the description. In the aunt sentence, you probably should have a comma - unless you mean that he went to visit his aunt whose name was Lady Aghaten rather than to another of his aunts named something else. With no comma, it is a defining clause; it distinguishes which aunt he visited.

In the second sentence, it's OK as it is. If it had begun, "He married the actress whose ...", you'd have to consider whether you needed a comma. Without the comma, it specifies which actress he married.