William, the duke of Normandy: 1048 to 1060

The sons of count Geoffrey are worthy, bellicose successors of their father, who dies in 1060 in the midst of your aggressive campaign to subject Anjou to your rule. This occupies the entire resources of Normandy, and only gains you further blows: the war will eventually peter out from the usual lack of decisive power held by either side: if you are not killed in the process, you will, nevertheless, be too old and weary to make any attempts on the throne of England. When your cousin king Edward dies, you cannot disentangle yourself from the Angevin/Manceaux/Breton conflict (yes, it escalated out of control, as these kinds of wars usually do), in order to raise an army of invasion. No "William the Conqueror" for you: more likely, history knows you only as William the (bloody) Bastard instead.