The Criterion Collection
Established in 1984, the Criterion Collection is dedicated to gathering together the "important classic and contemporary films" from around the world. The volumes they publish (originally as laserdiscs, switching to DVD in 1998, and including Blu-ray as of 2008) are known for their extremely high quality transfers and abundance of supplemental features. They have done much to set the stage for the ubiquity of multi-disk and "special" edition DVDs today, but continue to rise above most other releases and produce what are considered to be the definitive editions of some of our greatest films. (In order by spine number.)
Note: An alternate, alphabetical list can be found at: http://www.listsofbests.com/list/5623.
(Last update: December 19, 2012)