Prince Heinrich Wilhelm Konstantin Viktor Franz of Hesse-Kassel (English: Henry William Constantine Victor Francis of Hesse-Kassel) (or Hesse-Cassel) (30 October 1927 – 18 November 1999).
Prince Heinrich was born in Rome, Italy, the son of Prince Philipp of Hesse and Princess Mafalda of Savoy, daughter of King Victor Emmanuel III of Italy.
During the Second World War, Heinrich's father was arrested by the Gestapo and his mother was detained and imprisoned in Buchenwald concentration camp, where she was killed by Allies' bombardments in 1944. Heinrich and his siblings (Moritz, Otto and Elisabeth) were given sanctuary in the Vatican. After the war they were reunited with their father in Germany. Heinrich died in Frankfurt, unmarried.
See the references to Heinrich in J. Petropoulos, Royals and the Reich: the Princes von Hessen in Nazi Germany for more detail. He was an artist and set designer and also published a volume of memoirs, Der Kristallene Lüster (Munich, 1994).
Source: Wikipedia, "Prince Heinrich of Hesse-Kassel", available under the CC-BY-SA License.