The Vikings had slaves which made up the lowest of class of workers in Viking society. Oftentimes they were from Northern or Eastern Europe who were prisoners of war, or in debt, or born into slavery.
Most families owned one or two slaves. Thralls could be freed at any time, in a will, or buy their own freedom. There was still a gray area for a thrall when they became a ‘freedman,’ where they still owed allegiance to their former master and vote according to their wishes. This would last for two generations before their descendants became fully free.