German SA-Gruppenführer (“group leader”) who, in early 1933, was the SA leader in Berlin. Before joining the Nazi Party he had been a hotel bellboy and a bouncer at a gay nightclub.
In June 1931, he was described in the Socialist-Democratic Munich Post as one of Ernst Röhm’s best-known gay friends. Because of his longstanding relationship with Paul Röhrbein, who had helped him ascend within the Nazi party, Ernst was known as “Frau von Röhrbein”. Walther Stennes’ followers referred to the alleged homosexual trio as “Röhm-Röhrbein-Ernst”.
It has been suggested that it was Ernst who, with a small party of stormtroopers, passed through a passage from the Palace of the President of the Reichstag, and set the Reichstag building on fire on the night of 27 February 1933. However, the consensus of nearly all historians is that Marinus van der Lubbe did set the Reichstag on fire.
On 30 June 1934 Ernst had just married, and was in Bremen on his way to Tenerife to honeymoon with his new wife. SA Leader Ernst Röhm had repeatedly called for a “second revolution” that would introduce socialism into the Reich and banish the old Conservative forces of business and government. Fearing the socialistic tendencies of the SA, along with Röhm’s ambition to absorb the Reichswehr into the SA, conservative elements in the German Army and Kriegsmarine pressed for an elimination of SA power. Adolf Hitler—who had served as Ernst’s best man at his wedding six weeks earlier—undertook a purge of the SA, an event known to history as the Night of the Long Knives. It lasted until 2 July 1934.
Ernst was arrested in Bremerhaven together with his wife and his friend Martin Kirschbaum as he was about to get aboard a cruiser in order to travel to Tenerife where he planned to spend his honeymoon. Later on he was handed over to an SS-commando unit led by Kurt Gildisch, flown back to Berlin and taken to the barracks of the Leibstandarte Adolf Hitler, where he was shot by a firing squad in the early evening of 30 June at age 29.

Link to Wikipedia biography