The office of Groom in Waiting (sometimes hyphenated as Groom-in-Waiting) was a post in the Royal Household of the United Kingdom, which in earlier times was usually held by more than one person at a time – in the late Middle Ages there might be dozens of persons with the rank, though the Esquires and Knights of the Body were more an important and select group. Grooms-in-Waiting to other members of the Royal Family and Extra Grooms in Waiting were also sometimes appointed. For the general history of court valets or grooms see Valet de chambre.
From the time of the Restoration (1660), the king was attended by Grooms of the Bedchamber, whose functions as attendants on the monarch's person were performed in the reign of Queen Anne by Women of the Bedchamber. By the time of Queen Victoria, however, the majority of political offices no longer involving regular attendance on the sovereign, there were appointed, in addition to the Queen's Women of the Bedchamber, eight Grooms in Waiting who would discharge those political and social functions of the Grooms of the Bedchamber which could not be undertaken by the Queen's attendants of the female sex. After Queen Victoria's reign, the nomenclature of "Grooms in Waiting" was retained in preference to "Grooms of the Bedchamber".
One of the holders of the office was designated the Parliamentary Groom in Waiting from about 1859, when it became customary to appoint a Member of Parliament who was a supporter of the government of the day. In addition to his political functions, the Parliamentary Groom in Waiting was in attendance on the Queen with the other grooms. The office became vacant in 1891, when Lord Burghley was promoted to the similar political office of Vice-Chamberlain of the Household. The political office fell into disuse in 1892, since which time it has not been revived, although this did not affect the non-political, court position of Groom in Waiting.