From the time the first gasoline engine was fitted to motorcycles, guys have been adapting their bikes for offroad use.

Taking off parts like lights and horns, adding knobby tires and better suspension, no one man was credited with who invented vintage dirt bikes.

In 1885 Daimler and Maybach created a motorcycle that was different to what had come previously.

In 1914 Siegfried Bettman modified existing Triumph models to make something that resembled more of a dirtbike than Daimler and Maybach.

It wasn't until the 1940's that dirt bikes were more than just modified street bikes.

Here's a slideshow of some vintage dirt bikes:

Who invented vintage dirt bikes? By the late 1950's, early 1960's Honda was developing motorcycles that were more mainstream.

But the one who made the first dirt bikes was a company... Yamaha's DT-1 changed the sport forever.

The DT-1 was the first dirt bike to almost be capable of being ridden in any kind of terrain. The term dirt bike was forever changed by this bike that allowed bikers to take their motorcycle just about anywhere that could be walked.

So I guess you could say Yamaha is the company who invented the dirt bike, but vintage dirt bikes were made at home.