The oldest known lock was found by archeologists in the Khorsabad palace ruins near Nineveh. The lock was estimated to be 4,000 years old. It was a forerunner to a pin tumbler type of lock, and a common Egyptian lock for the time. This lock worked using a large wooden bolt to secure a door, which had a slot with several holes in its upper surface. The holes were filled with wooden pegs that prevented the bolt from being opened.
Famous Locksmiths
Robert Barron The first serious attempt to improve the security of the lock was made in 1778 in England. Robert Barron  patented a double-acting tumbler lock.
Joseph Bramah Joseph Bramah patented the safety lock in 1784. Bramah's lock was considered unpickable. The inventor went on to create a Hydrostatic Machine, a beer-pump, the four-cock, a quill-sharpener, a working planer, and more. Joseph Bramah
James Sargent In I857, James Sargent invented the world's first successful key-changeable combination lock. His lock became popular with safe manufacturers and the United States Treasury Department. In 1873, Sargent patented a time lock mechanism that became the prototype of those being used in contemporary bank vaults.
Samuel Segal Mr. Samuel Segal (former New York City policeman) invented the first jimmy proof locks in 1916. Segal holds over twenty-five patents.
Harry Soref Soref founded the Master Lock Company in 1921 and patented an improved padlock. In April 1924, he received a patent (U.S #1,490,987) for his new lock casing. Soref made a padlock that was both strong and chea using a case constructed out of layers of metal, like the doors of a bank vault. He designed his padlock using laminated steel.
Linus Yale Sr. Linus Yale invented a pin-tumbler lock in 1848. His son improved upon his lock using a smaller, flat key with serrated edges that is the basis of modern  pin-tumbler locks.
Linus Yale Jr. (1821-1868) American, Linus Yale Jr. was an mechanical engineer and lock manufacturer who patented a cylinder pin-tumbler lock in 1861. Yale invented the modern combination lock in 1862.
History Links
Schlage's History of Locks Locks and keys were known long before the birth of Christ. This website has an excellent coverage of lock and key history.
The History of Locks In the history of locks it is interesting and important to trace the means adopted to make the lock secure, as age succeeded age.
History of Locks and Keys The use of locks goes back to the beginning of recorded history. Men have always been concerned with protecting their property from others. Door locks are how people have protected their property.
Ancient Key Gallery The gallery has images of old keys and locks and history extracted from the Chubb Encyclopaedia of Locks and Builders Hardware - first published in 1958.
Locksmithing Throughout the Ages The first mechanical locks, made of wood, were probably created by a number of civilizations at the same time.
A Brief History of Locks in America During the period of the 18th and 19th century many technical developments were made in the locking mechanisms that added to the security of common locking devices.  It was during this period that America changed from importing door hardware to manufacturing and even exporting some.