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
A fun-looking elastoplast/band-aid pattern. A hint of orange tone in this one.
Source Josh Green
Super simple but very nice indeed. Gray with vertical stripes.
Source Merrin Macleod
Geometric lines are always hot, and this pattern is no exception.
Source Listvetra
From a drawing in 'Friend or Fortune? The story of a strange year', Robert Overton, 1897.
Source Firkin
A textured blue background pattern with vertical stripes.
Source V. Hartikainen
Prismatic Snowflakes Pattern 3 No Background
Source GDJ
Remixed from a drawing in 'Очерки Русской Исторіи въ памятникахъ быта', Petr Polevoi, 1879.
Source Firkin
Number 2 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
A heavy hitter at 400x400px, but lovely still.
Source Breezi
Sometimes you just need the simplest thing.
Source Fabricio
Prismatic Abstract Geometric Background 4 No Black
Source GDJ
Prismatic Abstract Line Art Pattern Background 2
Source GDJ
Simple wide squares with a small indent. Fits all.
Source Petr Šulc.
Based on several public domain drawings on Wikimedia Commons. This was formed from a rectangular tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i
Source Firkin
Cubes as far as your eyes can see. You know, because they tile.
Source Jan Meeus
A seamless marble-like texture colored in light blue.
Source V. Hartikainen
As simple and subtle as it gets. But sometimes that’s just what you want.
Source Designova
Drawn in Paint.net using the kaleidoscope plug-in and vectorised.
Source Firkin
Prismatic Groovy Concentric Background 3 No Black
Source GDJ
Produced using the clouds, flames and glass blocks plug-ins in Paint.net and the resulting .PNG vectorised with Vector Magic.
Source Firkin
A version without colours blended together to give a different look.
Source Firkin