the YF-118G Bird of Prey super secret stealth fighter is the most futuristic plane ever developed. The YF-118G Bird of Prey, a single-seater black project stealth aircraft, looks part F-22 Raptor and part science fiction-inspired deep space fighter. It never received an x-plane designation because it was never a true military test aircraft, but the tech it tested might later have been integrated into the F-22 and the F-35 fighters.
The Bird of Prey was officially ended before the turn of the 21st Century, even though it looks the part of an aircraft from this era.
https://www.youtube.com/watch?v=VzItY87qbqc