Fob watch

A fob watch was a watch carried in the pocket, as opposed to being worn on the wrist.

The Doctor's fob watches
The First, Seventh, Eighth and Eleventh Doctors all regularly wore and used fob watches. The Eleventh Doctor began to regularly wear a watch chain after going into retirement and continued wearing it after his return, when he changed his clothing style. (TV: The Bells of Saint John) It was generally a gold fob watch fastened to his waistcoats. (TV: The Day of the Doctor, The Time of the Doctor) The fob watch carried by the Seventh Doctor was the one used by the First Doctor. (PROSE: All-Consuming Fire)

Once, the Fourth Doctor used his fob watch for hypnotic suggestion. (TV: The Ribos Operation)

The Eleventh Doctor used a fob watch to lure Lepus Warriors through a warp gate. (COMIC: The Hat Trick)

Chameleon Arch
A crucial part of the Chameleon Arch looked like a fob watch. Chameleon Arch fob watches once held the Time Lord essences of both the Tenth Doctor and. Such watches were recognisable, as Martha Jones learned, by distinctive Gallifreyan messages on the obverse, and an engraving of a solar system (presumably Gallifrey) on the back. (TV: Human Nature, The Family of Blood, Utopia)

On meeting Jackson Lake and seeing his fob watch, the Tenth Doctor thought that Jackson might be an incarnation of himself. When the Doctor turned the watch over, however, it didn't bear any Gallifreyan script and was revealed as an ordinary fob watch. (TV: The Next Doctor)

Behind the scenes

 * Character Options made replica Tenth Doctor fob watches available in their 2007 toy range.
 * A metal version of the Master's Fob watch was released by Wesco and later it was re-released as 50th Anniversary Collectors FOB Watch for the 50th Anniversary, with a new clock face.
 * A more accurate Prop version of Metal Fob watch was released under the title "Chameleon Arch Pocket Watch" by The Celestial Toystore.