Count Odo of Paris (born c. 853) is a historical character, an ancestor of the subsequent Capetian dynasty of French kings. He successfully defended Paris against a Northmen army under a figure known as Siegfried, in the Viking siege of AD 885-86. However, the (succesful) siege attributed to Ragnar Lodbrok took place forty years prior, in AD 845, when Odo of Paris was not even born yet.
The father of the historical Count Odo also was not named Odo, but Robert. The Count of Paris at the time of Ragnar's historical siege was one Leuthard II, but his role in the event, if any, is uncertain.
In the French language his name is written Odon. Alternatively it is also named Eudes.
Odo was the Marquis of Neustria (northern France) as well as the Count of Paris. He may have held both posts because the Seine River linked Paris with the English Channel and was vulnerable to raids by both Norse Vikings and Celtic Bretons.
Odo commands the Heerbann, a Frankish military system where all free landholders capable of bearing arms were called upon to protect and fight for the Frankish realm in times of war.
The office of Count (Latin: Comes) was invested with both military and civil responsibilities in regard to governing a pagus (county). It wasn't until the 10th century CE when the increasingly decentralization of authority, and the rise of Manorialism, in western Europe led regional countships becoming more autonomous, until they had become hereditary fiefdoms by the 11th century.