A comeback for you: the popular Escheresque, now in black.
Source Patten
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
Very dark pattern with some noise and 45-degree lines.
Source Stefan Aleksić
Remixed from a JPG that was uploaded to Pixabay by theasad121
Source Firkin
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
One more updated pattern. Not really carbon fiber, but it’s the most popular pattern, so I’ll give you an extra choice.
Source Atle Mo
From a drawing in 'The Quiver of Love', Walter Crane, 1876
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
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
Seamless pattern made from a tile that can be obtained in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Prismatic Geometric Pattern Background 2 No Black
Source GDJ
This tiled background comes in red and consists of tiles that look like gemstones. It is more for blogs or social profiles, I think.
Source V. Hartikainen
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
Looks like an old wall. I guess that’s it then?
Source Viahorizon
Seamless Background For Websites. It has a texture similar to cork-board.
Source V. Hartikainen
From a drawing in 'Two Women in the Klondike', Mary Hitchcock, 1899.
Source Firkin
Light square grid pattern, great for a “DIY projects” sort of website, maybe?
Source Rafael Almeida
Clean and crisp lines all over the place. Wrap it up with this one.
Source Dax Kieran
Remixed from an image that was uploaded to Pixabay by CatherineClennan
Source Firkin
The classic 45-degree diagonal line pattern, done right.
Source Jorick van Hees
Derived from an image that was uploaded to Pixabay by TheDigitalArtist
Source Firkin