Oscar Fredrick Dronjak (born 20 January 1972) is a Swedish guitarist and founder of the power metal band HammerFall.

Prior to the success of HammerFall, he also played and released albums with the death metal acts Ceremonial Oath and Crystal Age.

His first instrument was the recorder; he then played trombone for a few years until, at the age of fourteen, he settled on guitar.

In 1989 he started a death metal band called Desecrator, which was later renamed Ceremonial Oath.

In 2016 he performed for the HammerFall album Dominion, which is scheduled to be released by Napalm Records on 16 August 2019.