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.

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.

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).