In division 1 NCAA football there is no official national champion, however the University of Alabama has won 8 AP poll national championships. the years where 1961, 1964, 1965, 1973, 1978, 1979, 1992, 2010. the school also claims 1925, 1926, 1930, 1934, and 1941 as national championship years because they were named NC's by polls such as BR, BS, CFRA, HAF, HS, NCF, PS, and others that are often not recognized. Alabama is also tied with Noter Dame for most NCs with 8. Noter Dame and USC also claim 11 NCs for reasons like alabama. Oklahoma claims 7 even though they have been named NCs 17 times by other polls.

This is in addition to the above information:

If we talk National Titles, it would depend on who you talk to. You the School claims 13 national titles, however, the College Football Data Warehouse (CFDW) only record 12 titles. This is because in 1941, there were 3-teams up for the National Title (Alabama at 9-2, Minnesota at 8-0 and Texas at 8-1-1). Back in 1941 there were 14 selctors that picked the National Champion. The voting went as follows;

11 selectors for Minnesota,

2 selectors for Texas and

1 selector for Alabama

The AP selector picked Minnesota, however, since 1 selector chose Alabama the school claimes the national title. The CFDW has Minnesota listed as the official Champion of 1941.

just to add to this:

The NCAA lists Alabama as receiving a championship for the 1945, 1966, 1975, and 1977 college football seasons but Alabama does not claim them, even though they have better records than some of the teams that did claim them.