He is buried at St. Guglows Cemetary, plot 572.
Like all ghosts, he is transparent, with his bones visible inside his body. He has a glowing skull.
He is slender build.
Ever since he was alive, Craigie had a severe sibling-rivalry with his sister Engilbjort, and this continued after both of them had died. Engilbjort resented him for the fact that their parents apparently favored him (though it's unknown if this is true or if she just perceived it that way), and left him an entire book collection.
For many years, since long before the start of the series, Craigie Williams visited Frida's house to read his favorite book, "The Legend of Great King Condon", which was now Frida's property. Since she loved the book as much as he did, he cleaned up her room for her every night. Frida never knew about Craigie and always thought her room cleaned itself.
At the start of Chapter 9, the book went missing and thus Craigie stopped comming, leading to Frida's room becomming a mess. Hilda, David and Frida eventually sought out Craigie at St. Guglows Cemetary because they tought he took back his book. He didn't, and suspected Engilbjort to be the thief. The three humans challenged Engilbjort to a wrestling match to get it back, but lost. Hilda eventually forced Engilbjort to return the book she stole by keeping her from going back into her grave, but it turned out the book she took was a different one: "The Squire’s Folly". With the book still missing, Craigie had no desire to go back to cleaning Frida's room.
Craigie is not seen for the rest of the series. In Chapter 13: The Black Hound, Hilda found "The Legend of Great King Condon" in the Nowhere Space of Frida's house and returned it to Frida's room. It's unknown if Craigie went back to visiting Frida after this.
- It's possible that the name of the character was inspired from the name of an author of one of the books that the creator Luke Pearson read, "Scandinavian Folk-Lore: Illustrations of the Traditional Beliefs of the Northern Peoples", written by William Alexander Craigie.