Known bearers of Barron as a given name include the American business magnate Barron Hilton (b. 1927), his grandson Barron Hilton II (b. 1989) and Barron Trump (b. 2006), the youngest son of the American businessman and president Donald Trump (b. 1946).
In the New Testament Simon is the name of several characters, including the man who carried the cross for Jesus. Most importantly however it was borne by the leading apostle Simon, also known as Peter (a name given to him by Jesus).
Because of the apostle, this name has been common in the Christian world. In England it was popular during the Middle Ages, though it became more rare after the Protestant Reformation.