As far as I know, William had no nickname. His sister did.
Bob
The nickname for Robert is obviously Rob because it is the first three letters of Robert that actually makes sense.
No, "Mac" is not a nickname for "William." "Mac" is traditionally a nickname for names like "MacDonald" or "MacKenzie."
William the Conqueror was the only but illegitimate son of Robert I, Duke of Normandy. Though illegitimate, his father named him as heir to Normandy. His illegitimacy affected his early life because he was nicknamed "William the Bastard" by his father's relatives, who also attempted to kill him. However, when Robert I died, he was recognized as heir to the Dukedom, but his enemies in Normandy dared also later in his life to nickname him in so offensive a way.
Robert is a idot his nickname is Dot Robert is a idot his nickname is Dot
Billy comes from the nickname for "William", and the meaning of William is "will helmet, protection". Bob comes from Robert; the meaning of Robert is "bright fame". However, both names being so short may imply different original meanings.
The origin of Bob as a nickname for Robert is not explicitly clear, but it is believed to have occurred through a process called rhyming slang, where the nickname was formed by simplifying the sound of the original name. This practice was common in British English nicknaming conventions.
Robert
William Robert Daly's birth name is William Robert Dailey.
Bill is a nickname for William.
He didn't have a nickname, he was from Scotland.