Sharp pixel pattern looking like some sort of fabric.
Source Dmitry
The tile this is formed from can be retrieved in Inkscape by selecting the rectangle and using shift+alt+i
Source Firkin
A seamless pattern created from a square tile. To get the tile, select the pattern in Inkscape and use shift+alt+i.
Source Firkin
Colour version of the original pattern inspired by the front cover of 'Old and New Paris', Henry Edwards, 1894.
Source Firkin
A bit like some carbon, or knitted netting if you will.
Source Anna Litvinuk
And some more testing, this time with Seamless Studio. It’s Robots FFS!
Source Seamless Studio
A free seamless background image with a texture of dark red "canvas". It should look very nice on web sites.
Source V. Hartikainen
Remixed from a design on Pixabay. To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
Source Firkin
Remixed from a drawing in 'Works. Popular edition', John Ruskin, 1886.
Source Firkin
Oh yes, it happened! A pattern in full color.
Source Atle Mo
From a drawing in 'Studies for Stories', Jean Ingelow, 1864.
Source Firkin
I took the liberty of using Dmitry’s pattern and made a version without perforation.
Source Atle Mo
Like the name suggests, this background image consists of a pattern of dark bricks. It may be an option for you, if you are looking for something that looks like a brick wall for use as a background on web pages. It's not a masterpiece, but looks pretty nice when is tiled.
Source V. Hartikainen
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Prismatic Abstract Geometric Background 2 No Black
Source GDJ
Bigger is better, right? So here you have some large carbon fiber.
Source Factorio.us Collective
Prismatic Abstract Line Art Pattern Background 2
Source GDJ
People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
Derived from an image that was uploaded to Pixabay by mdmelo.
Source Firkin
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A nice and simple white rotated tile pattern.
Source Another One
This one is rather fun and playful. The 2X could be used at 1X too!
Source Welsley
Remixed from a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
More bright luxury. This is a bit larger than fancy deboss, and with a bit more noise.
Source Viszt Péter
From a drawing in 'Heroes of North African Discovery', Nancy Meugens, 1894.
Source Firkin
A free seamless background image with abstract texture of green "curtain".
Source V. Hartikainen