Thor started out as a concept band in 1973. They used the names "Thor", "Centaur" and "Mikl Body Rock". These entities were the brainchild of Jon Mikl Thor, a vocalist, musician and body building champion who won titles such as Mr. USA and Mr. World Canada. He decided to combine muscle with music. In every show Jon Mikl Thor would appear as "Thor The Rock Warrior". Mikl Body Rock aka "Thor" toured throughout North America seeking fame and to garnish enough attention to secure a record deal. The press dubbed them "Kings of Muscle Rock" or "Warriors of Gladiator Rock".
In 1976 Jon Mikl met guitarist Frank Soda while touring Canada. Frank Soda joined "Thor" who also became known as "Thor and The Imps". The band toured constantly in the Eastern USA and Canada region building a large following. The first album was recorded in Toronto, Canada under the name Thor and was called Muscle Rock. Released by the independent label God Of Thunder Records, the record became a success, and gained the attention of various managers and producers who wanted to sign the act. Jon Mikl Thor was offered a large deal to star in a production at the Aladdin Resort & Casino in Las Vegas called 'Red Hot and Blue'. Frank Soda wanted to keep touring with the band, so Frank Soda and The Imps were formed. Jon Mikl Thor went on to star in Las Vegas and was discovered by Merv Griffin, who had Thor perform live on the Merv Griffin Show from Caesars Palace on national television. Thor's performance was a hit, and offers came in from various major labels. Thor decided to sign with RCA Records in late 1976.