The A-10 is ANOTHER story...

about how the Air Force neglected a fantastic, effective platform in preference for one that was sexier and faster...

The A-10 Thunderbolt is (as mentioned above) the premier tank killer - but it is slow, old, and basically incapable of air to air combat. It's primary weapon is a depleted uranium gatling gun that shreds armoured vehicles to pieces in a single pass - and is terrifying to the enemy. After Gulf War I, the Air Force decided that it wasn't sexy or fast enough for it's fighter jocks to fly, and decided that F-16s could use air to ground missles instead...so all the A-10s got slated for mothballs in the Arizona desert...

Funnily enough, when GW2 occured, the Air Force had to dust them all off and send them back to the desert, as it was quickly proven that F-16s fly too damned fast and high to be effective tank killers in close air support roles...