Nowadays, an ejection seat is a standard feature on just about any military aircraft (with the exception of some cargo ones). Interestingly enough, the modern layout for an ejection seat was first proposed not by someone associated with a major air power (e.g. Germany or Britain), but by a Romanian inventor Anastase Dragomir in the late 1920s.
The design, featuring a parachuted cell (a dischargeable chair from an aircraft), was successfully tested on 25 August 1929 at the Paris-Orly Airport near Paris and in October 1929 at Băneasa, near Bucharest.
However, the first aircraft to be fitted with such a system was the Heinkel He 280 prototype jet-engined fighter in 1940 (the first turbojet-powered fighter aircraft in the world). Unfortunately, persistent problems with its engines (initially with Heinkel and subsequently with BMW designs), led to it being passed over in favor of the now-famous Me-262.
It was one of the He 280 test pilots – Helmut Schenk – who became the first person in the world to escape from a troubled aircraft with an ejection seat on 13 January 1942 after his control surfaces iced up and became inoperative.
The first operational aircraft to provide ejection seats for the crew was (not surprisingly) also the one developed by Heinkel. It was He 219 Uhu (“Owl”) – the first dedicated night fighter – which was deployed in June 1943.
The first operational jet aircraft to be equipped with the ejection seat (of a new type – fired with explosive cartridge) was also the German WW2 design – and also by Heinkel. The Volksjäger (“People’s Fighter”) He 162 Spatz (“Sparrow”) which was quite a Wunderwaffe itself.
The only aircraft not developed by Heinkel that was equipped with an ejection seat was Dornier Do 335 Pfeil (“Arrow”) heavy fighter. Like He 162, it had a design feature that made the ejection seat a necessity.
Do 335 had a rear-mounted engine (of the twin engines powering the aircraft) powering a pusher propeller located at the aft end of the fuselage and thus presenting a hazard to a normal “bailout” escape.
He 162 had its jet engine (BMW 003) mounted on top of its fuselage behind the cockpit which also made normal “bailout” a very risky endeavor (to put it mildly).