What NFL teams have gone 15 1?

The 1984 San Francisco 49'ers: 15-1

The 1985 Chicago Bears: 15-1

The 1998 Minnesota Vikings: 15-1

The 2004 Pittsburgh Steelers: 15-1

The 2007 New England Patriots: 16-0

(The 72' Dolphins went undefeated but was prior to 16 game schedule)