Stefán grew up in Ólafsvík and lived there until over the age of 20. After school he did general manual labour and service jobs. To name a few, he worked in the fishing industry, did building work, plumbing, gardening, was a security guard, a cleaner, worked with teenagers and cared for the mentally ill.
He has now written eight novels, the first coming out in 1996, Dyrnar á Svörtufjöllum (The Door in the Black Mountains).