Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A repeating background of thick textured paper. Actually, it turned out to look like something between a paper and fabric.
Source V. Hartikainen
The following orange background pattern resembles a honeycomb.
Source V. Hartikainen
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Light gray pattern with an almost wall tile-like appearance.
Source Markus Tinner
Sharp pixel pattern looking like some sort of fabric.
Source Dmitry
I know there is one here already, but this is sexy!
Source Gjermund Gustavsen
Feel free to download and use it, or see the rest of the dark background patterns that I have made. Anyway, I hope you will find something that you like.
Source V. Hartikainen
With a name this awesome, how can I go wrong?
Source Nikolay Boltachev
Dark blue concrete wall with some small dust spots.
Source Atle Mo
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
I guess this one is inspired by an office. A dark office.
Source Andrés Rigo.
Remixed from a drawing in 'Works. Popular edition', John Ruskin, 1886.
Source Firkin
From a drawing in 'Picturesque New Guinea', J Lindt, 1887.
Source Firkin
Cubes as far as your eyes can see. You know, because they tile.
Source Jan Meeus
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
Free tiled background with colorful stripes and white splatter.
Source V. Hartikainen
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
A cute x, if you need that sort of thing.
Source Juan Scrocchi