Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
Remixed from an image that was uploaded to Pixabay by KirstenStar
Source Firkin
Used correctly, this could be nice. Used in a bad way, all hell will break loose.
Source Atle Mo
Colourful background achieved with gradient fills.
Source Firkin
Seamless Prismatic Quadrilateral Line Art Pattern No Background
Source GDJ
Classic vertical lines, in all its subtlety.
Source Cody L
From a drawing in 'Studies for Stories', Jean Ingelow, 1864.
Source Firkin
Dark and hard, just the way we like it. Embossed triangles makes a nice pattern.
Source Ivan Ginev
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Very simple, very blu(e). Subtle and nice.
Source Seb Jachec
Same as Silver Scales, but in black. Turn your site into a dragon with this great scale pattern.
Source Alex Parker
From a drawing in 'Heroes of North African Discovery', Nancy Meugens, 1894.
Source Firkin
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
ZeroCC tileabel stone granite texture, edited from pixabay. CC0
Source Sojan Janso
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Fix and cc0 to get the tile this is based on.
Source SliverKnight
The classic subtle pattern. Sort of wall/brick looking. Or moon-looking?
Source Joel Klein