Dokucraft is a texture pack created by the user Doku.
There are 3 different versions of Dokucraft and those are Light, Dark, and High. Light is the original pack that is high in detail. Dark is gloomy and desaturated with demonic decoration. High is an elven theme that has many shades of blue and a ton of ornate decorations.
Dokucraft is a HD Texture Pack so you will need to make sure to use MCPatcher to patch your copy of minecraft. The simple tutorial for that can be found here.