Tux is a penguin character and the official brand character of the Linux kernel. Originally created as an entry to a Linux logo competition, Tux is the most commonly used icon for Linux, although different Linux distributions depict Tux in various styles. The character is used in many other Linux programs and as a general symbol of Linux.
The concept of the Linux brand character being a penguin came from Linus Torvalds, the creator of Linux. According to Jeff Ayers, Linus Torvalds had a "fixation for flightless, fat waterfowl" and Torvalds claims to have contracted "penguinitis" after being nibbled by a little penguin on a visit to the National Zoo & Aquarium, Canberra, Australia, joking that the disease "makes you stay awake at nights just thinking about penguins and feeling great love towards them".
Linus spoke at the 1994 AUUG Conference (5-9 Sept, Melbourne) as part of a "World Tour" to Belgium, Australia, Singapore and elsewhere, mentioning in Linux Journal he was bitten by a penguin at Canberra Zoo, not at Phillip Island, Victoria, by a (shy) wild penguin.
In an interview Linus commented on the penguin bite:
I've been to Australia several times, these days mostly for Linux.Conf.Au. But my first trip—and the one when I was bitten by a ferocious fairy penguin: you really should keep those things locked up!—was in 93 or so, talking about Linux for the Australian Unix Users Group.
At Canberra zoo a sign said in 2009 that staff believed the "original Tux" was still resident in the penguin enclosure.
Apart from this, in the book Just for Fun: The Story of an Accidental Revolutionary, there is an excerpt dedicated to how Tux became the mascot of the Linux OS. In the book, Linus says he doesn’t remember how Tux became the mascot, but believes the zoo story, which, according to his wife, Tove Torvalds, is probably right.
The story, according to Linus, is that while Tove may in fact have vaguely mentioned penguins at some early stage, it was in a conversation with two high-ranking Linux types that the icy creatures were first seriously considered as the operating system’s official mascot.