Nanobox.js
fastest, tinyest lightbox

1KB ungzipped, unminified, 0 dependencies.

Seriously, just 1483 bytes of readable code.

Sources and how to use Click any image

Works with images and iframes

If link points to an image, it will be displayed in a lightbox. If it points to a page or even a youtube video, it will be displayed in a iframe (also in lightbox).