Hans Lippershey

Crude telescopes and spyglasses may have been created much earlier, but Lippershey is believed to be the first to apply for a patent for his design and make it available for general use in 1608. He failed to receive a patent but was handsomely rewarded by the Dutch government for copies of his design. A description of Lippershey's instrument quickly reached Galileo Galilei who created a working design in 1609, with which he made the observations found his Sidereus Nuncius of 1610.
There is a legend that Lippershey's children actually discovered the telescope while playing with flawed lenses in their father's shop, but this may be apocryphal.