Sketches by the acclaimed artist Cliff Wright, who illustrated the book Harry Potter And The Prisoner Of Azkaban, are to go under the hammer later this month.
The drawings are the instantly recognisable forerunners of the images, which appeared on the front and back covers of the second novel of JK Rowling's series.
The front illustration, which features the bespectacled wizard and his classmate Hermione Granger clinging to the back of hippogriff, is expected to fetch 13,000 pounds.
The second sketch, which features a snarling dog, is predicted to raise 11,000 pounds.
Wright said the images were completed in 1998.
"The images are part of a series of 10 which were sent to the publisher Bloomsbury as rough ideas for character development and composition," he said.
"Each drawing was submitted by fax and returned with comments. The designs were also passed on to JK Rowling for her approval and any comments passed back to me," the Scotsman quoted Wright as saying.
"On deciding the look of the characters and the picture composition, the watercolour illustration that you see on the cover was then completed, and when the book was published in the autumn of 1999 it became a global phenomenon," he added.
Micky Middleton of art firm Red Gallery is dealing with the sale and believes that it would attract a huge amount of interest.
"I would encourage collectors to come and see these original works at the Fair," he said.
The Glasgow Art Fair will run from Apr 23-26.