—Brandon Sanderson on Twitter on January 19th, 2012
The Wheel of Time Companion is an encyclopedia and guidebook to the world of The Wheel of Time. It was published in November 2015. It was written by Harriet McDougal, Robert Jordan's widow and editor, with the assistance of Maria Simons and Alan Romanczuk. Maria and Alan were Robert Jordan's writing assistants and fact-checkers during the writing of most of the novels of the main series. The book draws heavily upon Robert Jordan's unpublished notes and outlines for the series.
The companion is the second guide to the series to be published, following The World of Robert Jordan's The Wheel of Time, published in 1997. The companion is a new work, not merely an updated version of the older book.
The book features a comprehensive guide to many of the characters in the series, along with a 1,000-word vocabulary of the Old Tongue, new maps depicting the Last Battle (including one of Thakan'dar), new portraits of many of the characters, detailed information on the nations of the world, descriptions of flora and fauna, and information on the relative strengths of different channelers.
The book features new artwork commissioned by Irene Gallo at Tor Books.
During the publicity tour for Knife of Dreams in 2005, Robert Jordan announced his intention to release a new guide or encyclopedia once the main series was concluded. His plan was always to co-write it with Harriet. Following Robert Jordan's death, Harriet confirmed that she was continuing to work on the book and hoped to release it about a year or so after the publication of the final Wheel of Time novel. Initially referred to as The Wheel of Time Encyclopedia, Harriet announced the title change to The Wheel of Time Companion at the World Science Fiction Convention in London in August 2014.