Examples of planes that were classified as day fighters were the Supermarine Spitfire and Messerschmitt Bf 109. Both were excellent interceptors, but were also found in roles such as strike fighter and reconnaissance. Yet neither was really able to be used as a useful night fighter, so the term day fighter was used to describe designs of this sort.
Today almost all fighter aircraft have enough equipment to be used as a night fighter, so the term day fighter has fallen from use. Perhaps the last of the day fighters was the Northrop F-5 Freedom Fighter, a small plane that was capable of carrying out most missions including light bombing, strike and interception, yet included no radar. A number of companies have attempted to introduce similar designs but the market seems to demand more capable aircraft.