Roadrunner stalwarts like Sepultura's Max Cavalera influenced the likes of the Foo Fighters' Dave Grohl.

Roadrunner is a record label of extremes.

It looks after hugely popular rockers Nickelback, then, on the other hand, has uncompromising bands like Obituary, Opeth (who tour here in April), Cradle of Filth, Slipknot and Soulfly on its books.

Many fans of these latter bands prefer to ignore Nickelback's existence. But signing the multimillion-dollar Canadian band is a smart move because it helps keep the label healthy - and a few of these less savoury bands alive.

Roadrunner started 25 years ago and to celebrate the milestone it has reissued some of its key releases from different stages of its life.

While not dabbling in the excesses of extreme music like labels such as Relapse or Earache, Roadrunner has been responsible for some of the most influential metal and heavy music ever. The label's influence on the mainstream is also huge.

Foo Fighter Dave Grohl's Probot album from 2004 highlighted that, with appearances from, among others, King Diamond (of Mercyful Fate) and Max Cavalera (of Sepultura/Soulfly), both Roadrunner stalwarts.

But before we analyse the painted-face, and octave-straddling voice of King Diamond, it has to be said that every re-issue here comes with an extra disc - either DVD or CD - of live footage, extra tracks, unreleased material, remixes, and new liner notes. They are collectors' items and ideal for those who have worn their first, or second, copies out.

But back to King Diamond, an iconic vocalist in metal circles. His band Mercyful Fate formed in 1981. In 1983 they released Melissa which now, to be honest, sounds dated at times.

Evil is almost like a song by Survivor (remember Eye Of the Tiger from Rocky?). It also goes on a little in places with proficient, yet whining guitar solos, and over-indulgent instrumentals.

And by today's standards the King's high voice is laughably OTT, especially on Into the Coven when he shrieks, "Come, come, into my coven, And become Lucifer's child".

But back in 1983 Melissa was revolutionary. And the gallivanting Black Funeral, the nine-minute-long Satan's Fall, and the melodramatic metal of the title track is something special that makes you realise how a young Dave Grohl, and thousands like him, thought, "What the hell is this? I need King Diamond in my life."

After 1984's Don't Break The Oath, Mercyful Fate broke up over musical differences. And along came King Diamond with a more mature sound.

So, tracks like Mansion In Darkness and Omens, are more throbbing and, well, metal, and as a result, more palatable. King Diamond set a mighty benchmark.

Leap forward a few years and the metal scene had fragmented into thrash, death, grind core, hard core, black ... Fear Factory were the pioneers of industrial death metal - a fast, staunch and mechanical music. The band's first two albums, Concrete (not officially released until 2002), and Soul Of A New Machine, were ahead of their time because they pushed death metal in uncharted directions.

But it was Demanufacture that hit the nail on the head because the mix of brutality and pulverising beats with catchy riffs and the sung-versus-roared vocals of Burton C. Bell, won them huge cross-over success. Songs like Replica and Dog Day Sunrise still stand up as mainstream metal anthems to this day.

And finally we come to Max Cavalera, who, since leaving Sepultura in 1997, has been patchy because of an over-indulgence in the world music-meets-metal of his band Soulfly. More on them later, but with Sepultura, Roadrunner could have easily re-released the three albums before Roots.

True metal heads would agree that Beneath the Remains (1989) and Arise (1991) are classics, and Chaos AD (1993) isn't bad either. But if you're into something a little more diverse, and challenging, then Roots is it.

Merging the sounds of traditional instruments from Sepultura's Brazilian homeland, this is not only a brutally heavy record, but revolutionary. A pure classic thanks to songs like Roots Bloody Roots, Ratamahatta, and the cacophonous Straighthate.

At the end of last year Soulfly released Dark Ages, their best album since their first. Trouble is, there's been too many "worldy" albums in between.

What makes the self-titled debut so good is how it continues in the vein of Roots. It is frantic, pummelling, and tough, while still retaining those world music tinges and tribal beats. But mostly it is pure unadulterated metal.

Check out these reissues - especially Sepultura. As that band once said, its all about "roots, bloody roots", and that's what the Roadrunner label has. Good roots. Even if it does harbour Nickelback.