Wolframalpha has an ever-expanding collection of ‘parametric function’ portraits featuring noted figures, past and present.
They appear to be hand-drawn, but on closer inspection of the utterly complex parametric equations, seem to be digitally rendered instead.
To illustrate just how complex these equations are, here is a screen shot of part of the equation behind the Albert Einstein curve (first picture featured at the end of the article, with the unnamed kitty):
Can you identify the following people when they're represented in mathematical curves?
[via io9.com, images via Wolframalpha]