Interactive Timeline of the History of Linux
May 9, 1996
Tux was born
The concept of the Linux mascot being a penguin came from Linus Torvalds, who claims to have contracted penguinitis after being gently nibbled by a penguin:
Penguinitis makes you stay awake at nights just thinking about penguins and feeling great love towards them.
The Tux mascot was created by Larry Ewing in 1996 after an initial suggestion made by Alan Cox and further refined by Linus Torvalds on the Linux kernel mailing list.
The first person to call the penguin Tux was James Hughes, who said that it stood for (T)orvalds (U)ni(X). However, tux is also an abbreviation of tuxedo, the outfit which springs to mind when one sees a penguin. Source: Wikipedia