The following is a collection of locations ideal for finding free 3D models and texture maps for use in your game. While every site linked is not entirely free, every single one contains several free resources ready for use in your game.
3D Model Resources
To limit to just free models, go to the 3D category and search for something. You can then filter by price, including $0 as an option.
The Unreal Engine asset store is a fraction of the size of the Unity store. The majority of free content is directly from Epic, but is of an exceedingly high quality. The above link searches for just free content. Products are freely usable in personal and commercial projects as long as you use Unreal Engine.
TurboSquid is one of the oldest model resources on the internet and has a huge collection of free assets. The link above links directly to the free models, you can then filter down by addition requirements (rigged, poly count, etc)
OpenGameArt is a repository for free assets aimed at game developers. The above link is directly to the 3D objects section. This is an non-curated collection, so quality varies massively.
This site is dedicated to Blender and contains tons of Creative Commons licensed resources. You are given a daily download limit if not a member, although a free login option exists.
Sketchfab is quickly becoming the place to demonstrate your artistic abilities, with full WebGL previews available. The above link is for resources tagged as free and downloadable. Unfortunately their search interface makes searching for free assets needlessly complicated.
Google Poly is a resource for free 3D objects, with VR/AR in mind. Models tend to be low poly and flat shaded instead of textured.
CGTrader is another online game marketplace with a large number of free downloads available. The above link is for free assets only. Be careful of licenses, royalty free licensed assets can be used in commercial projects, while editorial licenses cannot be used in commercial products.
This is the Microsoft alternative to Google’s Poly. It’s aimed at Paint3D usage, so you have to open first in Paint 3D (a free Windows 10 only application), then export to a format such as FBX.
Yeah, that NASA. They have a large collection of space related models and textures available. Granted a very niche collection, but invaluable if you are making a space related game.
Another site with a huge archive of free 3D models for download. Currently over 130K models on the site.
Yobi isn’t a model site, it’s a search engine that searches free sites. It searches several different free sites. Be aware the license varies from site to site, so be careful before using results in a commercial project.
Texture Map Resources
A large collection of texture maps and images released under the Creative Commons Zero open source license.
A huge collection of textures also released under the CC0 license.
Free textures are limited to 15 downloads a day and higher resolution downloads require payment.
A huge collection of textures, two sites from the same source. Textures free and public domain.
Large collection, but quite dated at this point.
Megascans is a gigantic collection of commercial textures that offer a small subset of free textures linked above.
Large collection of textures, free to download individually, donate to receive a singular download archive link.
A large collection of free textures
Pixar released a large collection of cinema quality textures a number of years back. 128 common materials in the collection of extremely high detail.
Another large collection of textures, although of vastly varying quality.
A collection of game ready textures, the lower resolution versions are free to download while higher resolution versions require payment.
This collection is free for non-commercial use only!
A collection of textures on the site Blender Cloud, obviously Blender focused but not specific to Blender.
OpenGameArt is a collection of open source game assets, the above link goes directly to the texture section
Itch.io is a popular resource for indie game focused games and resources, the above link is for free resources tagged as textures.
Special textures for skybox generation, HDRI Haven has a huge collection for free downloads.
A tool for creating space field skyboxs programmatically.
Another tool, this one for programmatically creating planets.