(n.) One who passes; a passenger.

TV-viewer adventurer alpinist astronaut attestant attestator attester beholder bird-watcher bystander camper climber cojuror comers and goers commuter compurgator cosmopolite cruiser deponent drugstore cowboy earwitness excursionist explorer eyewitness fare gaper gazer gazer-on girl-watcher globe-girdler globe-trotter goer goggler hajji informant informer jet set jet-setter journeyer kibitzer looker looker-on mariner mountaineer observer ogler onlooker palmer passenger passer pathfinder perceiver percipient pilgrim pioneer rubberneck rubbernecker sailor seer sidewalk superintendent sightseer sojourner spectator spectatress spectatrix straphanger swearer televiewer television-viewer temporary lodger testifier tourer tourist trailblazer trailbreaker transient transient guest traveler trekker tripper viator video-gazer viewer visiting fireman voortrekker voucher voyager voyageur watcher wayfarer witness world-traveler