Prince Friedrich of Hesse and by Rhine

Prince Friedrich of Hesse and by Rhine (Friedrich Wilhelm August Victor Leopold Ludwig; 7 October 1870 – 29 May 1873) was the haemophiliac second son of Louis IV, Grand Duke of Hesse, and Princess Alice of the United Kingdom, one of the daughters of Queen Victoria. He was also a maternal great-uncle of Prince Philip, Duke of Edinburgh through his eldest sister Princess Victoria of Hesse and by Rhine.

Friedrich, called "Frittie" in the family, was a cheerful and lively child despite his illness. "Leopold" was added as one of his names in honor of his mother's hemophiliac brother, Prince Leopold, Duke of Albany, who was Friedrich's godfather.

His haemophilia was first diagnosed in February 1873, a few months before his death, when he cut his ear and bled for three days. Bandages could not stanch the flow of blood. In late May 1873, Friedrich and his older brother Ernst were playing together in their mother's bedroom. Ernst ran to another room, which was set at right angles to Alice's bedroom and peered through the window at his younger brother. Alice ran to get Ernst away from the window. When she was out of the room, Friedrich climbed onto a chair next to an open window in his mother's bedroom to get a closer look at his brother. The chair tipped over and Friedrich tumbled through the window, falling twenty feet to the balustrade below. Friedrich survived the fall and might have lived had he not been a haemophiliac. He died hours later of a brain hemorrhage.

Following Friedrich's death, his distraught mother often prayed at his grave and marked anniversaries of small events in his life. His brother Ernst told his mother he wanted all of the family to die together, not alone "like Frittie." Two of Friedrich's sisters, Irene and Alix, also had haemophiliac sons.