Spike Island is an inner city and harbour area of the English port city of Bristol, adjoining the city centre. It comprises the strip of land between the Floating Harbour to the north and the tidal New Cut of the River Avon to the south, from the dock entrance to the west to Bathurst Basin in the east. The island forms part of Cabot ward. The area between the Docks and New cut to the east of Bathurst Basin is in the neighbourhoods of Redcliffe and St Philip's Marsh.
Spike Island was created by William Jessop in the early 19th century, when he constructed the New Cut and converted the former course of the River Avon into the Floating Harbour. Until the Second World War, a lock connected Bathurst Basin with the New Cut, and Spike Island was a genuine island surrounded on all sides by water. However, fears that an aerial attack on this lock at low tide could lead to a disastrous dewatering of the docks led to the lock being filled in.
Historically, Spike Island was the site of working quays, shipyards, warehousing and other associated dockside industry. The Bristol Harbour Railway runs the length of the island, and formerly connected these working areas with the railway network.