Substantiv
observers [sing. an observer]
monitors [sing. a monitor]
watchers [sing. a watcher]
wardens [sing. a warden]
overseers [sing. an overseer]
comptrollers [sing. a comptroller]
watchmen [sing. a watchman]
keepers [sing. a keeper]
floorwalkers [sing. a floorwalker]
proctors [sing. a proctor]