The Tux family portrait. From left to right: Tux, Tux Crystal (Revision 1), Tux Crystal (Revision 2), Tiny Tux, and Crystalized Tux. They also have an illegitimate cousin in there (see http://en.wikipedia.org/wiki/Tux#QuickTime_penguin_controversy for more on this).
The backdrop is the Tux Crossing wallpaper. Unfortunately, it is uncertain who created this originally. The original Tux is drawn by Larry Ewing, the first Crystal Tux was by Everaldo, the second by Jan Vansteenkiste, and the crystalized Tux is by gg3po. The Tiny Tux is uncertain, but I believe it was by dlb