The Original Swamp Thing Saga (1977-1980, DC Comics)
Reprinted as part of the DC Special Series, which ran between 1977-1981. Reprints issues #1-10 in 4 comics, with some original cover art.

Swamp Thing (1982, Tor Books)
Released to coincide with the film release and Vol.2 of the print books. This collects issues #1-3, but only in black & white.
ISBN: 0523490127

Roots of the Swamp Thing (1986, DC Comics)
Published in 5 issues throughout 1986, this reprints issues #1-10 and House Of Secrets #92 (all of the Wein/Wrightson collaborations).

Dark Genesis (1991, DC Comics ; 2002, Vertigo)
First published in 1991, this collects #1-10 and House Of Secrets #92 in one volume. Republished a number of times, most recently by Vertigo in 2002.
ISBN: 1563890445

Secret of the Swamp Thing (2005, DC Comics)
A manga-sized collection, which only includes #1-10.
ISBN: 1401207987

Roots of the Swamp Thing (2009, DC Comics)
The first collection that includes Len Wein’s full run (#1-13, plus House Of Secrets #92).  Published a few times since then, in both hardback and paperback.  Includes an introduction by Len Wein.
ISBN: 1401222366 (hbk. 2009)
ISBN: 1401232876 (pbk. 2012)

Swamp Thing: The Bronze Age Omnibus (2017, DC Comics)
This huge book collects House Of Secrets #92, the whole first series (#1-24), and the beginning of the second series up until Alan Moore’s run (#1-19) including Annual #1 (the film tie-in).  Most of these issues had not previously been published in a trade paperback.
ISBN: 1401273785

Bernie Wrightson: Artifact Edition (2017, IDW)
A large-scale hardcover book featuring the artwork of Bernie Wrightson. Not a complete collection, but includes many un-inked or un-coloured pages of art from each of the Wrightson issues of Swamp Thing, plus House Of Secrets #92. It also includes covers and other artwork related to Swamp Thing.
ISBN: 1684052114

Swamp Thing: The Bronze Age (2018-, DC Comics)
DC decided to split up the ‘Bronze Age Omnibus’ into smaller books and add further content.  In addition to the material collected in the Omnibus, these volumes include Challengers of the Unknown #81-87 and The Brave and the Bold #122 and #176.  Vol. 2 also prints the script and unfinished art from the unpublished Swamp Thing #25 (1976) for the first time.
ISBN: 140128440X (vol. 1)
ISBN: 1401294227 (vol. 2)
ISBN: 177950716X (vol. 3)

Absolute Swamp Thing by Len Wein and Bernie Wrightson (2022, DC Comics)
Collects Len Wein’s full run (Swamp Thing #1-13, plus House Of Secrets #92). Includes an interview titled ‘The House That Swamp Thing Built’ (see Bibliography) and some other images, much of which had previously been published in Swampmen: The Muck-Monsters and Their Makers.
ISBN: 1779517300

Swamp Thing (1987-1989, Titan)
B&W reprints from the UK that include most of the Alan Moore run.  Collects Swamp Thing #21-64, and Annual #2, over 11 books.  Includes introductions by James Herbert, Clive Barker, Ramsey Campbell, Neil Gaiman, Charles Shaar Murray, and Stephen Bissette.

Swamp Thing (1987-1990, DC Comics)
DC published 2 books in the late 80s that collected some of the early Moore issues in colour, specifically #21-34 and Annual #2.  These were titled ‘Saga of the Swamp Thing’ and ‘Love and Death’.

Swamp Thing (1987-1990, Warner Books)
Warner Books published the same collection but with a different cover images.

Swamp Thing (1998-2006, DC/Vertigo)
By the late 1990s, Vertigo were reprinting the DC Alan Moore collections.  However, they didn’t stop with the first 2 books and continued publishing the complete Alan Moore run, most of which had only been available in the black & white Titan editions.  Books 7-9 also collected much of the Rick Veitch run for the first and only time to date.  In total, these 9 books collected Annuals #2-3 and issues #21-81 (up to the beginning of the time travel arc that culminated in Veitch’s departure).
ISBN: 1401202675 (bk. 7)
ISBN: 1401207936 (bk. 8)
ISBN: 1401210082 (bk. 9)

Saga of the Swamp Thing (2009-2011, Vertigo)
In 2009, Vertigo again reprinted the Alan Moore run, this time in a hardcover edition.  For the first time, this series included #20, Moore’s first issue.  These were later republished in paperback editions.  Collects #20-64 and Annual #2.
ISBN: 1401220827 (hbk., bk. 1)
ISBN: 1401225322 (hbk., bk. 2)
ISBN: 140122766X (hbk., bk. 3)
ISBN: 1401230180 (hbk., bk. 4)
ISBN: 0857685201 (hbk., bk. 5)
ISBN: 1401232981 (hbk., bk. 6)

DC Comics Graphic Novel Collection (2015-, Eaglemoss)
Eaglemoss have been releasing a collection of hardcover graphic novels for subscribers and, to date, there have been two issues devoted to Swamp Thing. These books collect House Of Secrets #92, and issues #21–34 and Annual #2 of the second series.
SKU: DCGUK065 (Swamp Thing Part 1, #65, Feb. 2018)
SKU: DCGUK071 (Swamp Thing Part 2, #71, Apr. 2018)

Swamp Thing Absolute Edition (2019-2022, Vertigo/DC Black Label)
The first Absolute Editions of Swamp Thing, these feature the oversize format and slipcase that is usual for the Absolute series. The first volume also includes an essay by Stephen Bissette with some of the original drawings and scripts. The colouring throughout has been completely re-done (and I personally do not care for it). The three volumes collect issues #20-64 and Annual #2 of the second series, plus DC Comics Presents #85.
ISBN: 1401284930 (vol. 1)
ISBN: 1779502826 (vol. 2)
ISBN: 1779512198 (vol. 3)

Swamp Thing by Nancy Collins · Omnibus (2020, DC Black Label)
Collects Swamp Thing #110-139 and Annuals #6 and #7, Black Orchid #5, and a story from Vertigo Jam #1.  It also includes Collins’ proposal for an unpublished series called ‘Arcane Blood’.
ISBN: 1401297099

Swamp Thing (2015-2016, Vertigo)
The Mark Millar run was collected into trade paperbacks.
ISBN: 1401252419 (#140-150)
ISBN: 140125828X (#151-160)
ISBN: 1401263372 (#161-171)

Swamp Thing (2004-2006, Vertigo)
These three books collect issues #1-6 and #9-20.
ISBN: 140120421X (bk. 1)
ISBN: 1401204937 (bk. 2)
ISBN: 1401209343 (bk. 3)

Swamp Thing (2012-2015, DC Comics)
The 2011 series was collected into seven volumes, which include #0-40, #25.1 (the Villains Month special), Animal Man #12 & #17 (part of the Rotworld Crossover), Aquaman #31, the ‘Futures End’ special, and Annuals #1-3.
ISBN: 1401234623 (bk. 1)
ISBN: 1401238432 (bk. 2)
ISBN: 1401242642 (bk. 3)
ISBN: 1401246397 (bk. 4)
ISBN: 1401250521 (bk. 5)
ISBN: 140125490x (bk. 6)
ISBN: 1401257704 (bk. 7)

There was also an oversize Deluxe Edition book released in 2015 which collects #0-18, Annual #1, and Animal Man #12 & #17 (the same issues as the first three trade paperback collections).
ISBN: 1401258700

Swamp Thing (2019, DC Comics)
Collects #1-10, Annual #1, and Animal Man #12 & #17.
ISBN: 1401290981

Swamp Thing: The New 52 Omnibus (2021, DC Comics)
Collects Swamp Thing #0-40 & 23.1, Annuals #1-3, Swamp Thing: Futures End #1, Animal Man #12 & 17, and Aquaman #31.
ISBN: 177950814X

Justice League Dark (2014-2015, DC Comics)
Swamp Thing’s adventures in the Justice League Dark team have also appeared in trade paperback collections.  Swampy started appearing from around #19.  Books 3-6 collect Justice League Dark #19-40, Annual #2 and the ‘Futures End’ special.  The Forever Evil: Blight TPB contains Justice League Dark #24-29, Constantine #9-12, Trinity of Sin: Pandora #6-9, and Trinity of Sin: Phantom Stranger #14-17, with Swampy appearing in many of these issues.
ISBN: 1401242456 (bk. 3)
ISBN: 1401250068 (Forever Evil: Blight)
ISBN: 1401247253 (bk. 4)
ISBN: 1401250076 (bk. 5)
ISBN: 1401254810 (bk. 6)

Swamp Thing (2016, DC Comics)
This collects the six issues that make up the Wein/Jones miniseries.
ISBN: 1401270018

Justice League Dark Vol. 2 (2019, DC Comics)
The first four books collect Justice League Dark #1-3, #5-6, #8-28 and Annual #1.
ISBN: 1401288111 (bk. 1)
ISBN: 140129460X (bk. 2)
ISBN: 1779500343 (bk. 3)
ISBN: 1779507143 (bk. 4)

Swamp Thing: Roots of Terror (2019, DC Comics)
This oversize collection includes Swamp Thing Winter Special #1 and stories from Swamp Thing Halloween Horror Giant, Cursed Comics Cavalcade #1, and Young Monsters in Love #1.
ISBN: 1401295878

Swamp Thing: Tales From The Bayou (2020, DC Comics)
The ‘Roots of Terror’ collection was later expanded to include the 7 issues from the first Giant series.
ISBN: 1779501153

Swamp Thing: New Roots (2021, DC Comics)
Collects the entirety of the digital series Swamp Thing: New Roots. The stories from issues #1-5 & #7-8 were previously released as part of the 2nd Giant series, but issue #6 and one story from issue #9 were previously unreleased in printed form.
ISBN: 1779511337

The Swamp Thing (2021, DC Comics)
Three trade paperbacks collect Future State: Swamp Thing #1-2 and The Swamp Thing #1-16.
ISBN: 1779512767 (bk. 1)
ISBN: 1779517165 (bk. 2)
ISBN: 1779520255 (bk. 3)

Swamp Thing: Green Hell (2023, DC Black Label)
Collects Swamp Thing: Green Hell #1-3.
ISBN: 1779517238