This background pattern contains a seamless texture of bark. It's not very realistic, but I think it looks quite nice.
Source V. Hartikainen
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
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
A comeback for you: the popular Escheresque, now in black.
Source Patten
If you like it a bit trippy, this wave pattern might be for you.
Source Ian Soper
ZeroCC tileable mossy (lichen) stone texture, edited from pixabay. CC0
Source Sojan Janso
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
A bit of scratched up grayness. Always good.
Source Dmitry
Prismatic Abstract Geometric Background 2
Source GDJ
Greyscale version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
More carbon fiber for your collections. This time in white or semi-dark gray.
Source Badhon Ebrahim
Sort of like the Photoshop transparent background, but better!
Source Alex Parker
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Prismatic Polyskelion Pattern No Background
Source GDJ
Inspired by a drawing seen in 'City of Liverpool', James Picton, 1883.
Source Firkin
As simple and subtle as it gets. But sometimes that’s just what you want.
Source Designova
Awesome name, great pattern. Who does not love space?
Source Nick Batchelor
Pass parameters to the URL or edit the source code variables to configure the graph paper for the division desired.
Source JayNick
Prismatic Hexagonalism Pattern No Background
Source GDJ
Looks like an old wall. I guess that’s it then?
Source Viahorizon
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
A seamless texture of black leather. I think it will look best when used in headers, footers or sidebars.
Source V. Hartikainen
Floral patterns will never go out of style, so enjoy this one.
Source Lasma