The Navy almost flew the Eagle off carriers
The Air Force has made the F-15 Eagle an icon of air superiority fighters. The Navy's F-14 Tomcat has its iconic status, thanks in large part to Top Gun and JAG, among other Hollywood productions.
But the Navy could have flown the F-15 off carriers. In fact, McDonnell-Douglas, who had made the iconic F-4 Phantom, which was in service with the Navy, Air Force, and Marine Corps, proposed what was known as the F-15N "Sea Eagle."
There was, though, a problem with the Sea Eagle. Aviation historian Joe Baugher notes that the design could not carry the AIM-54 Phoenix, which the Navy needed in order to counter Soviet long-range bombers armed with heavy anti-ship missiles.
The track records of both planes are nothing to sneer at. The F-14 proved to be a superb addition — it never had to face the big fight with the Soviet Union, but it nevertheless scored five air-to-air kills in United States Navy service. The F-15 scored 104 air-to-air kills with no losses across all operators, including the United States Air Force and Saudi and Israeli planes.
Here's a video showing just what might have been, and why it didn't happen.