It seemed pretty unusual for a one loss defending national champ to not get a chance to actually defend their title so I went back and looked to see if I was right. I went back 25 years, so I'm sure there are more there, but this is the era of matching up 1 and 2 as close as possible:  

2015 Ohio State

2013 Alabama (one loss no conference championship)

2009 Florida (one loss no conference championship, although de facto play in game)

1996 Nebraska

1994 Florida State (one loss and one tie)

Some pretty rare company here and Meyer owns two of them now. In all cases dynasties that didn't live up to potential but in some cases still lived on for many years after. Keeps it in perspective!