The Black Sabbath frontman died yesterday, aged 76, and fans around the globe paid tribute to the "Lovable Prince of Darkness".
Major fan and University of Otago music production senior professional practice fellow Hugh Harlow described Osbourne as "one of the founding fathers" of heavy metal.
Mr Harlow said he had spent the past 27 years working as a sound engineer in recording studios and live productions with heavy metal bands in the United Kingdom and New Zealand.
He said Osbourne and Black Sabbath’s influence on the heavy metal genre was "enormous".
"Many people would claim that he and the other members of the band essentially established the genre of heavy metal.
"There were other acts around the same time in the late 1960s, that you can also point to as being quite influential as the originators of heavy metal, but Black Sabbath really combined all of the elements that became central to the genre from that point on."
When they released their second album, Paranoid, the band had started to "lean into their innovations", he said.
"Guitarist Tony Iommi down-tuned his guitars, largely because of his plastic fingers.
"He lost the tips of his fingers in an industrial accident in Birmingham when he was 17, and found it easier to play guitars when all the strings had been tuned down.
"It made the strings slacker and easier to play. And that is now a staple of heavy metal.
"It also led to a darker sound that people embraced. It matched the lyrics about magic and Satan and all that stuff."
"They harnessed a lot of that industrial depression, doom and desperation.
"They were anti-establishment and quite transgressive against societal norms."
He said Osbourne’s on-stage and off-stage antics - like biting the head off a bat during a 1982 concert in Des Moines, Iowa - also threw him and the band into heavy metal folklore.
"It's one of those things that really made him stand out as a performer.
"It was the combination of all those things that they pulled together, that really led to this thing called heavy metal."
Mr Harlow believed the world was lucky to have been able to farewell Osbourne at a recent Black Sabbath tribute concert, where he and the band performed with some of the largest rock and metal bands from around the globe.
During his appearances on The Osbournes reality TV show, many people saw a man who was suffering the effects of "certain overindulgences" earlier in his career.
"But the thing I found really fascinating was that even when he clearly was confronting certain issues, as soon as he stepped on stage, that all melted away.
"The contrast between that image of what we saw on television, of a shuffling, slightly confused older man, was really contrasted with an energetic and focused performance.
"Music was really a big part of him."
The event culminated with Osbourne performing Mama, I'm Coming Home, which was from his solo career.
"Arguably, it was one of the most emotional and touching performances I've ever seen come from Ozzy and from Black Sabbath.
"I don't know whether he was necessarily aware that he was going to die, but certainly, that performance felt like a genuine farewell.
"Ozzy and the band really paved the way for other heavy metal bands.
"So we have lost one of the founding fathers of heavy metal."
