8 by 8 pixels, and just what the title says.
Source pixilated
People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Simple wide squares with a small indent. Fits all.
Source Petr Šulc.
And some more testing, this time with Seamless Studio. It’s Robots FFS!
Source Seamless Studio
There are quite a few grid patterns, but this one is a super tiny grid with some dust for good measure.
Source Dominik Kiss
The original enhanced with one of Inkscapes's filters.
Source Firkin
Utilising a bird from s-light and some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Crossing lines with a subtle emboss effect on a dark background.
Source Stefan Aleksić
The basic shapes never get old. Simple triangle pattern.
Source Atle Mo
This is the remix of "Background pattern 115" uploaded by "Firkin".Thanks.
Source Yamachem
Fake or not, it’s quite luxurious.
Source Factorio.us Collective
Dark, lines, noise, tactile. You get the drift.
Source Anatoli Nicolae
I love the movie Pineapple Express, and I’m also liking this Pineapple right here.
Source Audee Mirza
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Did anyone say The Hoff? This pattern is in no way related to Baywatch.
Source Josh Green
This could be a hippy vintage wallpaper.
Source Tileable Patterns