Robert E Howard only wrote a few Conan stories and even fewer novels. His original works were published in Weird Tales during the 1930's.
The Phoenix on the Sword
The Scarlet Citadel
The Tower of the Elephant
Black Colossus
The Slithering Shadow
The Pool of the Black One
Rogues in the House
Shadows in the Moonlight
Queen of the Black Coast
The Devil in Iron
The People of the Black Circle
A Witch Shall be Born
Jewels of Gwahlur
Beyond the Black River
Shadows in Zamboula
The Hour of the Dragon
Red Nails
He also wrote four Conan novels during that time as well, but they were not published when he was alive having been rejected by the publishers or not presented for publication.
The Frost Giant's Daughter
The God in the Bowl
The Vale of Lost Women
The Black Stranger
There were several Conan stories that were not completed at his time of death (he committed suicide in 1936)
The Snout in the Dark, fragment
Drums of Tombalku, fragment
The Hall of the Dead, synopsis only
The Hand of Nergal, fragment
During the 1950's Gnome Press published his short stories for the first time but it was not until the 1960's that Lancer press published all his works including the uncompleted ones that were reworked by L Sprague De Camp and Lin Carter. De Camp and Carter also wrote several stand alone novels and stories featuring our favourite Cimmerian.
Other authors also wrote Conan novels. some were great and others truly awful.
Of late, there are several editions available that have published pure Howard Conan but before spending your hard earned money though, you might want to try Mobileread's superb library first
https://www.mobileread.com/forums/sho...=robert+howard
https://www.mobileread.com/forums/sho...=robert+howard
Hope that helps