The Berserker series was written by Robert Holdstock under the pen-name Chris Carlsen. It was noted on the covers that these books were "From the publishers of Conan", as if that was somehow any more recommendation than if I was to note that Bear Alley is "Published on the internet, like the Pottermore website".
The Berserker series was about Norse warrior Harold Swiftaxe, a violent occult fantasy that has more in common with 2000AD's Slaine than Conan.
Sphere 0722-14631-0, 1977, 160pp, 65p. Cover by Melvyn Grant
Sphere 0722-14632-9, 1977, 175pp, 85p. Cover by Melvyn Grant
Sphere 0722-14633-7, 1978, 172pp, 95p. Cover by Melvyn Grant