On Swedish runestones the name is usually written Hakun and in medieval documents usually Haquon or in the Latinised versions Haqvin/Haqvinus.
Although in some western regions the name can be found as Håkon and Håka as late as in the 18th century.
For example, the Primary Chronicle mentions the Varangian leader Yakun that arrived in Kievan Rus' in the year 1024 and fought in the Battle of Listven.
The name never became popular as a Slavic name but at least two high rank Novgorod officials had the name: the posadnik Yakun Andreevich (Cyrillic: Якун Андреевич) (mentioned 1167) and the tysyatsky Yakun Namnezhich (Cyrillic: Якун Намнежич) (mentioned 1214).
An old English name form Hacon has survived in English placenames like Haconby which literally means Hacon's Village, originating through Norse settlers in England.