2011 NCAA Final Four, #8 seed Butler, facing #11 seed Virginia Commonwealth.
1985 NCAA Final Four, #8 seed Villanova, defeated #1 Georgetown to win the National Championship.
1980 NCAA Final Four, #8 seed UCLA, lost to #2 Louisville in the National Championship game.
2010 Duke
As of the 2008 March Madness, that was 2006 when Florida (3 seed), UCLA (2 seed), George Mason (11 seed), and LSU (4 seed) made the Final Four. That also happened in 1980 when Louisville (2 seed), UCLA (8 seed), Purdue (6 seed), and Iowa (5 seed) made the Final Four.
Since the 64 team structure, Virginia made it to the final 4 in 1984 as a number 7 seed.
2011 is the first time
They were an 11 seed.
In 2006, George Mason made it as a #11 seed. This is not necessarily the lowest seed of all time to make it to the final four.
No.1 seed
There have been three times in NCAA Men's Basketball history that no #1 seed has been in the Final Four. The only three years were 1980, 2006, and 2011 with the following teams included in their separate final fours: 1980: Louisville (#2 seed), Iowa (#5 seed), Purdue (#6 seed), and UCLA (#8 seed) 2006: UCLA (#2 seed), Florida (#3 seed), LSU (#4 seed), and George Mason (#11 seed) 2011: Butler (#8 seed), UConn (#3 seed), VCU (#11 seed), and Kentucky (#4 seed)
There have been three times in NCAA Men's Basketball history that no #1 seed has been in the Final Four. The only three years were 1980, 2006, and 2011 with the following teams included in their separate final fours: 1980: Louisville (#2 seed), Iowa (#5 seed), Purdue (#6 seed), and UCLA (#8 seed) 2006: UCLA (#2 seed), Florida (#3 seed), LSU (#4 seed), and George Mason (#11 seed) 2011: Butler (#8 seed), UConn (#3 seed), VCU (#11 seed), and Kentucky (#4 seed)
11
This has never happened. In 2006 and 1980 there were no number 1 seeds, but both years there was one number 2 seed remaining. 2011 was the first year that there was no number 1 or number 2 seeds that made the final four.
I believe that it was #1 UCLA and #2 Michigan.