Wiki: https://en.wikipedia.org/wiki/Mandelbrot_set
Here are a bunch of other visualizations: I don't know how artistic or data-driven some of these are, but they look very interesting. I think the nebula-looking one measures how often a point is visited?
The Bulbic Mandelbrot Set
https://www.deviantart.com/metafractals/art/The-Bulbic-Mandelbrot-Set-811453986
A Nebulabrot
https://mathematica.stackexchange.com/questions/89458/how-to-make-a-nebulabrot
