distort GUI.Box rect shape?

hi, i dont know what the simplest method of doing this is, but is there a way of altering a a rectangles shape? ive got a health bar but im bored with it being a simple rectangle so i was hoping to have the box taper off on 1 side ... something along the lines of "Left height=50" "right height=20" "width=100", i hope that makes sense

GUI.Box(new Rect(100,100, 100,20), "HP");

thanks for any help on this

 

Textures with alpha channel would be one way to go.