Aside from August, Marlena, Al, Camel, and Walter, the other people who work at the circus sort of blend together in a whirl of performers, roustabouts (workers who don't always last that long), and muscle. Individually, they sometimes seem like two-dimensional sketches, like the sideshow acts that some of them are. They flicker in and out of the narrative, appearing when it's truly necessary. Combined, they're more than the sum of their parts – they make a whole circus.
The Lovely Lucinda is a sideshow "freak" and fat lady who succumbs to a premature death. Al turns her funeral into a glorious parade that drums up business for the show like nothing else. Other ladies working the show include Barbara, a stripper and sometime prostitute who tries to help Jacob lose his virginity, and Nell, another lady of questionable virtue. The only other female performer we really meet is Lottie, who always knows the down-low when it comes to payday.
Muscle guys on the turf include Ezra, Blackie, and Earl. Blackie can't be trusted, but it turns out Earl can. Both of them are supposed to work for Al and Al alone, but Earl helps Jacob out when he and Marlena are in the most danger.
Sideshow announcer Cecil is joined under the tents by guys with colorful names like Diamond Joe and Crazy Joe. Grady and Greg are two of the many guys who work with the animals, including Rosie. Greg helps Jacob figure out that Rosie speaks Polish, while Grady gives Jacob important information at key moments in the book – like letting him know that Walter and Camel have died. Bill is a worker who was thrown off the train with Walter and Camel. Unlike them, he survived and came back to take revenge on Al.
These are all minor characters in comparison to the stars of the show. Without them, though, the story would be a lot less colorful and feel much less authentic.