Generation 4.5 (projected to remain relevant with Gen 5 concepts)
F-40 Warhawk II
An Air Superiority Fighter turned Multirole. Essentially if the F-22 had been introduced a decade earlier, and was a Fighting Falcon with a face lift.
Strip away the stealth paint and digital cockpit, the Raptor would still be a very formidable fighter. However, in 1986, it was apparent that F-22 would not be ready for service for another 2 decades. An interim was needed, no waiting for technology to catch up. Intended to be a more conventional stealth fighter, the ‘Warhawk’ has proven itself not only to dominate the skies, but as a force multiplier popular with ground forces. With a large payload and respectable loitering ability, she is truly a force to be reckoned with.
Aside from the shiny gold cockpit reducing radar returns from inside, Warhawk's stealth comes solely from its geometry. Because of this, design had to focus on maximizing stealth from certain angles rather than all around. From above and below, radar reduction is minimal, but from the front and back, the Warhawk II nearly vanishes from radar screens.
Noticeably heavier than the equally small F-16, Warhawk II's powerplant had to produce twice as much thrust compared to the Viper's. So it does. And then some more. Thrust to weight reaches 1.1 on dry thrust, and exceeds 1.6 on afterburners. All this while having 2D thrust vectoring, a beastly engine needs to chug jet fuel like no tomorrow. Luckily F-40 has the fuel reserves and efficiency to perform intercontinental trips at transonic speeds without refueling, and can run its engine on high bypass to increase efficiency further and reduce exhaust temperature, and IR signature.
Notes: I just got back into KSP after nearly a year hiatus, so if you notice anything hilariously stupid please let me know. Something like this should have internal bays, but such a design produces too much drag in Kerbin's air.