HARRY Potter actor Alan Rickman complained about his role as Severus Snape and said he was "frustrated" by a lack of character development, a stash of personal papers has revealed.

The British star, who died in 2016 aged 69, worried about the wizard's "narrative" and made notes under the heading "Inside Snape's Head", according to The Sun .

Despite his gripes, the BAFTA-winner held onto all eight scripts from the hit series, which will be auctioned alongside letters.

One postcard, from producer David Heyman, said: "Thank you for making [Harry Potter 2] a success. I know, at times, you are frustrated but please know that you are an integral part of the films. And you are brilliant."

Rickman was terrifying as Professor Snape.
Rickman was terrifying as Professor Snape.

The actor himself wrote about the character's development.

"It's as if [director] David Yates has decided that this is not important in the scheme of things ie teen audience appeal."

Other items in the $1.68 million collection include a handwritten Christmas message from a young Daniel Radcliffe and a letter from Nicole Kidman.

Another letter from author JK Rowling, penned after 2011's Deathly Hallows Part II, said: "Had to send a line about what you wrote in the souvenir program for Hallows II. Made me very tearful.

"Thank you for doing justice to my most complex character."

This story originally appeared in The Sun and is republished here with permission.