Book Series Which Outlived the Author

JRR Tolkien died in 1973, leaving his magnum opus "The Silmarillion" unfinished; it was completed by his son Christopher and published in 1973. Robert Jordan, author of the "Wheel of Time" series, died before the series was completed. At the request of the Jordan estate, and using notes left by Jordan, Brandon Sanderson successfully completed the series. This list includes other series of books which have continued after the death of the original author.This list does not include "Fan Fiction" but rather those series which have continued with the permission of the author or the author's family or estate.