But for many he will always be remembered as The Demon Headmaster in the hit CBBC show about a villainous school teacher with terrifying green eyes.
For those not of the generation that watched children's TV in the 90s, here's a reminder of why The Demon Headmaster remains in the minds of those who did tune in...
How The Demon Headmaster terrified a generation
The show launched on CBBC in 1996 based on the popular series of children's books by Gillian Cross.
The story follows a young girl Dinah (played by Frances Amey) who moves in with a new foster family and starts going to St Champions school, where things seem very sinster.
The children talk like robots and behave very strangely and even Dinah finds herself doing odd things that she doesn't quite feel in control of.
Dinah soon works out that The Headmaster has the power to hypnotise people with his spooky green eyes and is using his abilities to control the pupils, teachers and parents with the aim of world domination.
Dinah and her friends form SPLAT - The Society for the Protection of Our Lives Against Them - and take on the Demon Headmaster and his minions in a bid to stop him taking control of their lives.
The TV show would make viewers feel they might fall under the powers of The Demon Headmaster as his green eyes filled the screen transmitting hypnotic images into their homes.
Hardiman was unforgettable in the role with his emotionless face, piercing eyes and deep, ominous voice.
He wore shaded round spectacles and when he removed them his eyes would glow bright green.
While made for and aimed at children the Bafta-award winning drama was classed in the horror category with classic sequences of chase scenes, unseen threat and high tension.
The sci fi series also featured an eerie theme tune with high-pitched whistling sounds not unlike Doctor Who and The X Files.
The Demon Headmaster featured a fictional computer game Octopus Dare, that all the children were hooked on, but turned out to be a creation of the Demon Headmaster to entrap Dinah - perhaps an ominous foretelling of the dangers of screen time on the young.
And on Christmas Day 1997 a recording of the CBBC live pantomime The Demon Headmaster Takes Over TV was broadcast - teasing that no one was safe from the powers of The Demon Headmaster.
In the mundane setting of a school, with the villain controlling the minds of the adults in the children's everyday lives, and simple, low-budget special effects, it was undeniably Hardiman's powerful performance that made The Demon Headmaster so frightening.
Children were made to question their safety from the authority figures around them and perhaps now parents themselves they still quake in fear if they ever encounter a head teacher in dark glasses....