People brought to the parade and arena by audience vote, masked as monsters and doomed to stand in for the beasts they wear.
Stand-Ins are individuals brought to the eleventh-floor arena and judging stands 'by audience vote,' wearing the masks of the monsters they represent but arriving as themselves — bankers, politicians, elites, orcs, and others. Unlike the memory-echo Horribles, Stand-Ins register as real dots and can struggle: those in the judging stands are tied up and writhing, and Florin notes the AI breaks the crawlers' legs to punish a weak float. In the arena the Stand-Ins come as-is, unmasked into whatever they portray and outnumbered a hundred to one by real mobs that give no quarter — Carl watches panther mobs run down a masked woman revealed as an orc, unsure whether the dead are truly dead or teleported back to the eighteenth-floor resort.
The AI reduces them to interchangeable fodder: 'It doesn't matter who they are. They're all the same in the end.' They are central to the arena's coming boss fight and to Carl's two stand-in 'choices.'
People in monster masks — masked as goblins, manatees, and beasts — otherwise ordinary in mixed dress, some bound and struggling.
Audience-vote captives masked as monsters, doomed fodder for the arena's boss fight and Carl's stand-in choices.