How to make one:
Open Gimp and create a new 75x75 image with a transparent background. The default color is black, so don't worry. Use the Brush tool and with size 17 normal create the head.(click once) Use the size 07 normal brush to create the rest of the body, then go to
Filters>
Alpha to logo> (near bottom)
Alien Glow
From there tweak the glow size to 50 and the color staying at green, by default, unless you want something cool and unique. After performing that, delete the layer "Background" and you will automatically have transparency. Save it as main.png, and follow all of the default exporting options.