('formal') The person to 'whom' we spoke to was very helpful. = ('formal') The person 'whom' we spoke to was very helpful. = (more commonly) The person 'who/that' we spoke to was very helpful.
('formal') Her brother, 'whom' I met last year, is an attorney. = (more commonly) Her brother, 'who' I met last year, is an attorney.
('formal') To 'whom' did you speak? = ('formal') 'Whom' did you speak to? = (more commonly) 'Who' did you speak to?
(..) ~ And when I succeed... become king of Norway... I can cut my hair and I can marry you. I'm already married. To whom are you married, my beauty? Him? Is he a king? No. He's... An Jarl in Denmark. (..)2017 TvShow: Vikings Title: Revenge Season: 4 Episode 18