Christopher Paul O'Neill is an American-British financier and the husband of Princess Madeleine, Duchess of Hälsingland and Gästrikland, the second daughter and youngest child to King Carl XVI Gustaf of Sweden.
O'Neill was born in London to Paul Cesario O'Neill (1926–2004), an American investment banker who came to London in the 1960s to set up the European head office of Oppenheimer & Co, by his second wife, Eva Maria (born Eva Maria Walter in 1940, Austria). O'Neill has two half-sisters on his mother's side: Tatjana d'Abo and Countess Natascha von Abensberg-Traun, and three on his father's side: Stefanie, Annalisa and Karen. He grew up in London and St. Gallen, as well as in Austria and Germany, and holds dual American and British citizenship.
O'Neill was educated at Institut auf dem Rosenberg in St. Gallen, Switzerland, and graduated with a BA degree in International Relations from Boston University. He also obtained an MBA from Columbia Business School in New York.
Unlike his brother-in-law and sister-in-law, Prince Daniel and Princess Sofia, O'Neill is untitled and undertakes no royal duties, since members of the Swedish Royal Family must hold Swedish citizenship, which O'Neill has declined.