Champions of UFC who never lost titles in fights

Sport.ru/MMA. In UFC and in general in any MMA organization, the champion has to be overthrown that the new was crowned. It is a typical way of transition of titles from hand to hand. Unfortunately, sometimes there are situations when champions cannot leave in oktagon to protect the titles. That is even worse, some situations compel promotion to make decisions, and as a result the defending champion who, apparently, is adjusted on long stay at top of the division, instead loses the title. Irrespective of, whether these situations are caused by inaction or positive tests for a dope...