A flightless aquatic bird.
In the wild they are restricted to the southern hemisphere, with many nesting on Antartica, where there are no land-based predators so their flightlessness is not a disadvantage.
LinusTorvalds likes penguins, so the Linux 'mascot' is a penguin (named Tux.) He actually got given a penguin for Christmas in 1996, which is kept in his honour at the Bristol Zoo. See http://penguin.uk.linux.org/.