Numerous heavy metal bands can boast of genre defining greatness, but only one can have its formidable legacy evoked by a single shouted word: SLAYER! (It's as universal and versatile a word as DUDE!) And, as one of thrash metal’s cornerstone bands for the past 30-odd years, there is little about Slayer that is not widely broadcast and accepted gospel (forgive the anti-pun), so it was no small challenge to pick out 20 Facts You Probably Didn't Know About Slayer.

1 Slayer’s debut album, ‘Show No Mercy,’ was fittingly recorded close to the midnight hour, in a series of overnight sessions – in part for cost-saving, in part so drummer Dave Lombardo could finish High School.

2 After ‘Show No Mercy’s’ release, Slayer set out on their first tour of U.S. clubs in singer-bassist Tom Araya’s Camaro, with a U-Haul trailer in tow.

3 A punk rock aficionado, Slayer guitarist Jeff Hanneman started a short-lived hardcore band in 1984 with Dave Lombardo and Suicidal Tendencies guitarist Rocky George. They were called Pap Smear.

4 While still trying to establish their career, Slayer had to contest the legal right to use their very name with another heavy metal band from San Antonio, later known as S.A. Slayer.

5 The hypnotic chants heard at the onset of Slayer’s sophomore album, ‘Hell Awaits,’ are backwards recordings of the words “Join us!”

6 Half of Slayer's founding lineup was not born in the U.S. Tom Araya was born in Vina del Mar, Chile, and Dave Lombardo in Havana, Cuba, before immigrating to America, and joining many other Latin musicians in pioneering the 1980s thrash metal scene.

7 In 1987, Slayer recorded a frantic cover version of the psych-rock classic 'In-A-Gadda-Da Vida' for inclusion in the ‘Less Than Zero’ movie soundtrack.

8 Back in the ‘80s, guitarist Paul Crook, who is known for his work with Anthrax, Meatloaf and others, put in time as Kerry King’s guitar tech.

9 Tony Scaglione, who temped for Dave Lombardo in the late ‘80s, was a member of New Jersey thrashers Whiplash — whose other two members were named Tony Portaro and Tony Bono. Only in New Jersey ...

10 Judas Priest’s ‘Dissident Aggressor’ is the only cover version to be found on one of Slayer’s official studio albums (‘Undisputed Attitude’ not included).

11 Jeff Hanneman attributed his fascination with military history, as evidenced on classic Slayer cuts like ‘Angel of Death’ and ‘War Ensemble,’ to being raised in a family filled with war veterans.

12 The ‘Seasons in the Abyss’ song ‘Born of Fire’ was almost released as an instrumental, but guitarist Kerry King eventually threw together some lyrics at the 11th hour.

13 Dave Lombardo’s 1992 departure from Slayer was instigated by his desire to witness the birth of his child, at a time when the band was slated to tour.

14 Slayer’s 7th album, ‘Diabolus in Musica,’ is named after a sinister-sounding musical interval that was literally banned by religious authorities during the middle ages, and later found its way into the song ‘Black Sabbath’ by the homonymous heavy metal godfathers.

15 Kerry King plays the last solo heard on ‘Goddamn Electric’ from Pantera’s final studio album, 2000’s ‘Reinventing the Steel.’

16 Slayer’s eighth studio album was to have been titled ‘Soundtrack to the Apocalypse,’ but the band ultimately decided to save it for their 2003 box set, and came up with ‘God Hates Us All’ instead.

17 Artist Larry Carroll has designed no less than four Slayer album covers: ‘Reign in Blood,’ ‘South of Heaven,’ ‘Seasons in the Abyss,’ and, most recently, 2006’s ‘Christ Illusion.’

18 Collectors’ editions of Slayer’s tenth album, ‘World Painted Blood,’ feature maps made out of human skulls and bones – a concept that evolved from an old plan to base packaging on the infamous Sedlec Ossuary — a medieval chapel filled with some 50,000 human skeletal remains.

19 For a time, Kerry King devoted some of his spare time away from Slayer to…breeding show dogs.

20 In the Showtime series ‘Californication,’ novels written by the lead character — an author played by actor David Duchovny — were titled ‘South of Heaven,’ ‘Seasons in the Abyss,’ and ‘God Hates Us All.’

Bonus: Check Out Our 'You Think You Know Slayer' Video Compilation 20 Facts You Probably Didn't Know About Black Sabbath