A.k.a Tuomas Kuosmanen, a GIMP guru extraordinaire and the Supreme Rulah of Gradients!
Tigert has contributed many, many cool pixels for the open source community; For example, Wilber was his creation, as are many GIMP 1.1 splash screens, "Grokking the GIMP" cover, and many GNOME icons. He has also made many great GIMP tutorials.
Home page: http://tigert.gimp.org/