Lord Henry Wotton was one of Dorian's oldest friends. The two first met through Basil Hallward when Basil was creating his infamous portrait of Dorian. Henry became Dorian's friend and inspiration on the road to his long life of debauchery and hedonism.
Lord Henry also lead a scandalous life though to a lesser degree than Henry. In the end it cost him his marriage and his friendship with Dorian cost him standing in society.