Tux, the Linux penguin
Original Tux illustration by Larry Ewing, at: http://isc.tamu.edu/~lewing/linux/
Redrawn in Inkscape by Garrett LeSage: https://github.com/garrett/Tux
Public domain http://creativecommons.org/publicdomain/zero/1.0/
...but, if anyone asks:
Tux was originally made by Larry Ewing in the Gimp and re-illustrated in vector by Garrett LeSage, using Inkscape.