Jeremy Clockson is the temporal double of Lobsang Ludd, and son of Time and Wen the Eternally Surprised. He appears in Thief of Time. Separated from his double at birth, he was was delivered by Nanny Ogg and left on the doorstep of the Clockmakers Guild in Ankh-Morpork and raised there, while his brother Lobsang was left with the thieves' guild. He shows an amazing aptitude for his adoptive craft.
Jeremy is a dedicated craftsman to the point of being very little else; his workshop is utterly spartan, he has no friends and few acquaintances, and a conversation of a few minutes is described as exceptionally long. His obsession with accurate timekeeping leads him to overreact violently to a fellow clockmaker who intentionally sets clocks fast, with implications that he has committed murder and is therefore now watched over carefully by the authorities of the Guild, who insist on keeping him medicated and supervised. He appears, unlike his "twin", to have no natural ability for manipulating and subverting the ordinary flow of time, and instead to have the opposite ability of being incredibly aware of and obsessed with time's ordinary flow, with an intuitive understanding of "what time it is" at any given moment. His desire to count the ticks of time is what led to time's freezing into stasis, just as Lobsang's manipulation of time to attempt to prevent this is what led to time being thrown into shattered chaos.
He becomes the unwitting antagonist of the novel when he is hired by Lady Myria LeJean (one of the Auditors) to build the Discworld's second truly accurate clock, since he is not aware that such a clock will stop time as happened when the original truly accurate clock was built in the Uberwald. The clock he builds is constructed entirely from glass, and is designed to tick with the "tick of the universe"; however, since the universe is destroyed and recreated every moment, the clock can only count the tick if a part of it is constructed outside reality itself, thus causing it to freeze mid-destruction. This relates to the idea of Planck time, and the philosophical problems this causes when applied to Zeno's paradoxes. In Thief of Time, these ideas are attributed to the Discworld philosopher Xeno of Ephebe.
Injured in the events accompanying the clock's completion, Jeremy's heritage keeps him mobile in a timeless world but he's not properly conscious. Lobsang finds and touches him, and the two merge to form the current personification of Time, named Lobsang as he/they feel(s) that Lobsang had the happiest memories. It was also mentioned that he/they "never liked the name Jeremy even when (he) was Jeremy". Clockson's name appears to be a pun upon the name of the British broadcaster Jeremy Clarkson, as both are equally fanatic about their interests (clocks and cars respectively) - although Clockson's character bears more of a resemblance to the 18th century clock-maker John Harrison, the inventor of the marine chronometer.