"KiCad Like a Pro, 2nd Edition" written by Dr. Peter Dalmaris from Tech Explorations is great reference for KiCad users of all skill levels. This book covers everything from getting started using KiCad to using git for project version control. A special edition of this book has been created of which half of the profits from each sale will be donated to the CERN & Society Foundation for KiCad development.
Several text-based tutorials as well as video tutorials have been put together by various KiCad users. Here you can find a limited subset.
Hierarchical schematics as schematic buildingblocks by Bernd Wiebus. (Original in german)
A KiCad Quick-Start Tutorial by Windsor Schmidt (~20 mins)
Video series by Ashley Mills, complete with building from source and designing a board (12 parts ~5 hours)
Videos by Chris Gammell at Contextual Electronics (7 parts ~2.5 hours)
Fast screencasts without audio by Matt Venn, useful for workshops (5 parts ~15 mins)
Lots of short videos by My 2µF, mostly on PCB layout
Videos by Xplore Labz on creating an Arduino Uno