William Cromer (occasionally also spelt Crowmer) (1386 ― January, 1434) was an English Sheriff and Lord Mayor of London and a Member of Parliament for the city.^[1]

He was described as the son of John Cromer of Aldenham, Hertfordshire but was probably originally from Cromer, Norfolk. By 1390 he had settled in London, where he became a prosperous merchant.

William had a son also named William Cromer in 1416.

He was Warden of the Drapers Company by 1394, and again in 1428–29. He was appointed Auditor for London for 1399-1400 and 1409–11 and elected an alderman of Billingsgate Ward by 1403 until after July 1420 and of Candlewick Ward from 1420 until his death. He was elected a Sheriff of London in 1405–06 and Lord Mayor of London for 1413–14 and 1423–24.

During his public life he benefitted from a number of profitable commissions from 1407 onwards, when he was also elected to Parliament as member for the City of London (1407, 1417 and May 1421).