Haircraft Studio is a Blender add-on built around a hair library that can add a hairstyle into a scene in seconds. It ships with 113 hairstyles and the collection is still expanding, and different hairstyles can be customized for more variety.
The add-on includes a set of tools for producing and editing hair. You can summon hair, change its color, change the curve, change the shader, twist it, convert it to mesh, and set a custom curve. Color, shader and pattern options are available for customization, and the developer notes better optimization to keep scenes lighter.
Haircraft Studio is Blender extension compatible for Blender 4.0 to 4.5, distributed under the GPL license and using the Blender-Internal render engine. The developer is a Dev Fund contributor, and it holds a 5-star rating from 6 reviews. Documentation is available, along with a demo video.