Shawn Ogg is the youngest son of Gytha Ogg and Sobriety Ogg (although no one stops to consider the inconvenient fact that Sobriety died a good ten years before Shawn's birth, but .. then again, if a witch was doing the telling, then it must be right... only ignorant outsiders would raise this point, and are generally hushed up). That being the case, there is no consensus about who his father is and Sobriety makes as good a public father figure as any., He first appears in Wyrd Sisters as a guard at Lancre Castle. Since then he has become Lancre's entire standing army (except when he's lying down), as well as the civil service and most of the palace staff. Depending on the time of day or week, he is the Captain of the guard, the rest of the guard, the Commander-in-chief of the army, the Herald, the Royal historian, the Assistant butler, the Conductor of the Lancre Light Symphony Orchestra, the Postman and the Master of all the dirty jobs, particularly the cleaning of the privies. He also acts as a general handyman for the region, doing odd jobs from gardening to cooking. He is a great believer in protocol, complaining when people don't give him enough time to play all the roles necessary.
He is a short man, who has guarded the castle all of his working life. Due to the dull days (Lancre is not a place likely to be invaded by any barbarian hordes) and an unusually repetitive diet of cabbage, Shawn is not only extremely self-reliant, but also musically flatulent.
According to Nanny Ogg's Cookbook he has been granted the Order of the Lancrastian Empire. He is also notable for inventing small and almost pointless devices including the Lancrastian Army Knife (an obvious pun on the famous Swiss Army knife) which includes (at the King's behest) such attachments as "A Device for locating things that are lost" and "A Device to Remove the fundamental point from any argument".