The internet sometimes makes a big deal out of an overlooked fact, and today is no different. The official website for The Legend of Zelda series updated some of their character profiles and in one of those profiles, added in a factoid that had been missing for sometime. Ganondorf Dragmire has been the official full name of Ganondorf dating back to A Link to the Past, as his last name was detailed out in the manual.
However, this little nugget has been lost to time with little acknowledgement from Nintendo until now. Long may Ganondorf Dragmire reign.
Source: Official Site