If your invitation says “and Guest,” then yes, if not, we would prefer it if it was just you. Those who attend that have not been accounted for will be expected to bring a lawn chair and a sack lunch.
Although several people have asked if they can wear a costume, we would prefer to save that for the Halo-weekend! We are going to have a casual wedding (ideally no jeans or denim speedos, I'm talking to you, Wyatt). E.g. cocktail dresses, jumpsuits, slacks.