Why not have a fancy dress party and invite guests to wear Letter S Costumes. Explore this section to find your favourite fancy dress starting with the letter S. Costumes starting with the letter S range from Santa to skeleton or even Supergirl. As you can imagine, this is a consonant with so many possibilities. Become the Smallville superhero Clark Kent with our collection of Superman costumes which are available in a number of sizes. Surgeon costumes, medical scrubs, and sailor girls, we have a whole horde of ideas for Letter S costumes.