Herr Christopher Paul O'Neill, is a British-American financier and husband of Princess Madeleine, Duchess of Hälsingland and Gästrikland, with whom he has three children. He declined to become a Swedish citizen and accept any titles; he could then continue as a businessman with no royal duties.

Princess Madeleine of Sweden, Duchess of Hälsingland and Gästrikland is the second daughter and youngest child of King Carl XVI Gustaf and Queen Silvia. Upon her birth, she was third in line of succession to the Swedish throne; currently, she is eighth. Princess Madeleine is married to British-American financier Christopher O'Neill. They have three children, Princess Leonore, Prince Nicolas and Princess Adrienne.