This article lists the islands in the River Thames, or at the mouth of a tributary (marked †), in England. It excludes human-made islands built as part of the building of forty-five two-gate locks which each accompany a weir, and islets subordinate to and forming part of the overall shape of another. The suffix -ey (pronounced today ) is common across England and Scotland and cognate with ait and meaning island, a term – as ait or eyot – unusually well-preserved on the Thames. A small minority of list entries are referred to as Island, Ait or Eyot and are vestiges, separated by a depression in the land or high-water-level gully.
Most are natural; others were created by excavation of an additional or replacement navigation channel, such as to provide a shorter route, a cut. Many result from accumulation of gravel, silt, wildfowl dung and plant decay and root strengthening, particularly from willows and other large trees. Unlike other large rivers, all today are considered fixed. All in the reaches below Lechlade have been protected against erosion by various combinations of canalisation of the river, building up with dredged material from the river bed, water reeds, concrete, cement, wood or sheet piling.
List of islands
thumb|right|Sheppey - Minster from Elmley Marshes
thumb|right|Oliver's Island looking downstream
thumb|right|Glover's Island from Richmond Hill
thumb|right|Raven's Ait from Queen's Promenade
right|thumb|Platts Eyot - Port Hampton
thumb|right|Ham Island - The Cut
thumb|right|Bavin's Gulls and Cliveden
thumb|right|upright|Temple Island, Henley
The islands are listed in order upstream from the sea.
{| class="wikitable sortable"
|+ Islands from the sea to Thames Head and published size:
|-
! data-sort-type="text" | Name
! data-sort-type="number" | Area<br>(acre)
! date-sort-type="number" | Area<br>(ha)
! class="unsortable" | References
|-
|Isle of Sheppey†||||
|-
|Two Tree Island† (also known as Leigh Marshes)||||
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|Canvey Island†||||
|-
|Lower Horse Island† on Holehaven† a sandbank of Holehaven Creek, Corringham||||
|-
|Upper Horse Island
|1.97
|0.8
|
|-
|Chiswick Eyot, Chiswick||||
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|Oliver's Island, Strand-on-the-Green||||
|-
|Brentford Ait, Brentford||||
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|Lot's Ait, Brentford||||
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|Corporation Island, Richmond||||
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|Glover's Island, Twickenham||||
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|Eel Pie Island, Twickenham||||
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|Swan Island, Twickenham||||
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|Trowlock Island, Teddington||||
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|Steven's Eyot, Kingston upon Thames||||
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|Raven's Ait, Surbiton||||
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|Boyle Farm Island, Thames Ditton||||
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|Thames Ditton Island, Thames Ditton||||
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|Tagg's Island, Hampton||||
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|Benn's Island, Hampton||
||
|-
|Grand Junction Isle, Sunbury||||
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|Rivermead Island, Sunbury||||
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|Sunbury Lock Ait, Walton on Thames||||
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|Wheatley's Ait, Sunbury-on-Thames (also known as Wheatleys Eyot)||||
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|Desborough Island, Walton-on-Thames||||
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|D'Oyly Carte Island, Weybridge||||
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|Lock Island, Shepperton||||
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|Laleham Burway including Abbey Mead, Chertsey||||
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|Penton Hook Island, Laleham||||
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|Truss's Island, Thorpe||||
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|Church Island, Staines-upon-Thames||||
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|Hollyhock Island with Holm Island, Staines-upon-Thames||||
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|The Island, Wraysbury||||
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|Friary Island, Wraysbury||||
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|Friday Island, Old Windsor||||
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|Romney Island, Windsor||||
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|Cutlers Ait, Windsor||||
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|Jacob's Island, Windsor||||
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|Deadwater Ait, Windsor||||
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|Pigeonhill Eyot, Bray||||
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|Boulter's Island or Boulter's Lock Island, Maidenhead||||
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|Formosa including manmade Mill and Sashes Islands, Cookham||||
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|Black Boy Island, Hurley||||
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|Magpie Island, Medmenham||||
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|Temple Island, Remenham||||
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|Rod Eyot, Henley-on-Thames||||
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|Buck Ait, Sonning||||
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|Long Ait, Sonning||||
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|View Island, Reading||||
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|De Bohun Island, Reading||||
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|Appletree Eyot, Tilehurst||||
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|Long Wittenham Backwater Island||||
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|Fidder's Elbow far northern section||||
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|Swan Inn, Rose, Kennington or St Michael Isle, Kennington||||
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|Osney Island, Oxford||||
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|Radcot Bridge Upper Island, Radcot||||