Bulova Accutron Astronaut
In May 1963 during the Mercury 7 mission Gordon Cooper took his Bulova Accutron GMT into the space. Watch soon got the additional Astronaut mark. Cooper took the same watch into the space in August 1965 on Gemini V mission. Later also Gus Grissom and John Young wore Accutron on Gemini III mission in March 1965 and even Norman Thagard in 1983 in the Challenger Space Shuttle.
Watch is also tehnically interesting since it uses tuning fork powered by the battery cell instead of hairspring and it is by this a predecessor of quartz watches.