Well, truth be told, AC/DC and Motörhead are both debatable when it comes to classifying them into music genre, AC/DC are usually considered more as hard rock and Lemmy liked to claim they were punk rockers, I also wouldn't label few others mentioned as metal.
Now, that being said, the line between hard rock and metal is as blurry as my eyesight the morning after New year's and the main reason I brought it up was because I was bored, cranky and felt like nitpicking.
That said, the listed are legendary bands, although I can't say I ever listened to Highway Robbery. Just went to see Iron Maiden few days ago on their EU tour though and man, can the old gents still play. Also caught AC/DC a few years back and I guess I was lucky, since Brian Johnson had to leave them soon after. Unfortunately wasn't lucky enough to not miss Lemmy's last tour. :/ As for the Lordi, I still remember when they managed to win the Eurovision song contest and I have to say their's was the only Evrovision song I ever liked. x'D