When considering which Vikings series to watch first, it is generally recommended to start with the original 'Vikings' series, created by Michael Hirst, which aired from 2013 to 2020. This series provides a rich narrative that introduces viewers to iconic characters such as Ragnar Lothbrok, Lagertha, and Bjorn Ironside, exploring their journeys, ambitions, and the cultural context of the Viking Age. Watching 'Vikings' first allows viewers to grasp the complexities of Norse mythology, the social structures of Viking society, and the character development that is pivotal to the story. After completing the original series, you can transition to 'Vikings: Valhalla,' a sequel set 100 years later, which continues the exploration of Viking adventures, expanding on themes and characters introduced in the original series. This order enhances your viewing experience, as you will have a solid foundation in the Viking lore and the historical backdrop that influences the events of 'Valhalla.'