There have been many F5 tornadoes. See the link below for a list.

There have been several dozen F5 tornadoes since record began in 1950. F5 the highest level on the Fujita scale which runs from F0 to F5 and rates tornadoes based on the severity of the damage they cause. A rating of F5 denotes an extremely violent tornado that rips houses clean of their foundations. F5 tornadoes are typically large and have been known to destroy entire towns. They are absolutely devastating. The majority of the most famous tornadoes were F5's, though a few F4 tornadoes have made it onto the list.

Generally yes. F5 is the strongest category of tornado capable of completely obliterating well built structures. However how bad a tornado is depends on factors other than strength, such as where the tornado hits. For example, a number of F5 tornadoes have traveled over open country, with the worst damage limited to farms that were destroyed.

A list of the worst tornadoes in U.S. history will consist mostly of F5 or EF5 tornadoes (including the #1 worst), but several F4 tornadoes would be on that list as well.

A little more than 1% of tornadoes are rated F4 and F5 with F5 tornadoes being less than 0.1%

Tornadoes fluctuate in intensity. An F5 tornado is only at F5 strength for part of the time it is on the ground.