This list basically exists because I am occasionally forgetful and need to be able to confirm whether or not I already own something when out in shopping for comics etc.

DC Comics
Absolute Batman Long Halloween
All-Star Batman and Robin PB
Arkham Asylum- Madness HC
Arkham Asylum PB
Arkham Asylum Living Hell PB
Batgirl Greatest Batgirl Stories Ever Told PB
Batman A Death in the Family PB
Batman Anarky PB
Batman Arkham Asylum PB
Batman Arkham Origins PB
Batman Batgirl PB
Batman Battle for the Cowl HC
Batman The Black Glove HC
Batman The Black Mirror HC
Batman Broken City PB
Batman Broken Mirror PB
Batman Bruce Wayne Murderer? PB
Batman Cacophony HC
Batman Cataclysm PB
Batman Dark Knight Returns
Batman Dark Knight Strikes Again
Batman Dark Victory PB
Batman Dead to Rights PB
Batman Death and the Maidens PB
Batman Death of the Family HC
Batman Detective Comics Faces of Death
Batman Earth One
Batman Ego and Other Tales PB
Batman: Europa HC
Batman Faces
Batman Face the Face PB
Batman Gates of Gotham PB
Batman Going Sane PB
Batman Gotham After Midnight PB
Batman Gotham Underground PB
Batman Harley and Ivy HC
Batman Haunted Knight PB
Batman Heart of Hush HC
Batman Hush Volume 1 PB
Batman Hush Volume 2 PB
Batman Hush Returns PB
Batman Jekyll And Hyde PB
Batman Joker’s Last Laugh PB
Batman Joker’s Asylum Volume 1 PB
Batman Joker’s Asylum Volume 2 PB
Batman Killing Joke HC
Batman Knightfall Volume 1 Broken Bat PB
Batman Knightfall Volume 2 Who Rules the Night PB
Batman Knightfall Volume 3 Knightsend PB
Batman Lovers & Madmen PB
Batman Mad Love and Other Stories HC
Batman No Man’s Land Volume 1 PB
Batman No Man’s Land Volume 2 PB
Batman No Man’s Land Volume 3 PB
Batman No Man’s Land Volume 4 PB
Batman No Man’s Land Volume 5 PB
Batman Private Casebook PB
Batman Return of Bruce Wayne HC
Batman RIP Deluxe Edition HC
Batman Rules of Engagement HC
Batman Secrets PB
Batman Streets of Gotham Hush Money PB
Batman Streets of Gotham House of Hush HC
Batman Streets of Gotham Leviathan HC
Batman Through the Looking Glass HC
Batman Under the Hood 1 PB
Batman Under the Hood 2 PB
Batman War Drums PB
Batman War Games 1 PB
Batman War Games 2 PB
Batman War Games 3 PB
Batman Year 1 PB
Batman Year 2 Two-Face & Scarecrow PB
Batman & Robin- Batman Reborn HC
Batman & Robin- Batman vs Robin HC
Batman & Robin- Batman & Robin Must Die HC
Batman & Robin- Dark Knight vs White Knight HC
Batman and Robin Born to Kill HC
Batman and Son PB
Batman/Joker Switch PB
Birds of Prey- Platinum Flats PB
Catwoman Crime Pays PB
Catwoman Long Road Home PB
Catwoman Trail of the Catwoman PB
Catwoman When in Rome PB
Flashpoint PB
Flashpoint World of Flashpoint featuring Batman PB
Gotham City Sirens Volume 1 PB
Gotham City Sirens Volume 2 PB
Gotham Central Unresolved Targets PB
Greatest Joker Stories Ever Told
Harley Quinn Preludes and Knock Knock Jokes HC
Harley Quinn Welcome to Metropolis PB
Harley Quinn Night and Day PB
Harley Quinn Vengeance Unlimited PB
Harley Quinn Volume 1 Hot in the City PB
Harley Quinn Volume 2 Power Outage PB
Harley Quinn Volume 3 Kiss Kiss Bang Bang PB
Harley Quinn Volume 4 A Call to Arms PB
Harley Quinn Volume 5 The Joker’s Last Laugh HC
Harley Quinn & Power Girl PB
Harley & Ivy PB
Injustice Gods Among Us Year One Complete Collection PB
Injustice Gods Among Us Year Two Complete Collection PB
Injustice Gods Among Us Year Three Book One PB
Injustice Ground Zero HC
Joker HC
Joker Greatest Joker Stories Ever Told PB
Joker Death of the Family PB
Joker/Mask PB
JLA Earth 2 HC with Blu-ray/DVD
JLA Salvation Run PB
New Suicide Squad Volume 1 Pure Insanity PB
New Suicide Squad Volume 2 Monsters PB
New Suicide Squad Volume 3 Freedom PB
New Suicide Squad Volume 4 Kill Anything PB
New Teen Titans Judas Contract PB
Red Hood Lost Days PB
Suicide Squad Volume 1 Kicked in the Teeth PB
Suicide Squad Volume 2 Basilisk Rising PB
Suicide Squad Volume 3 Death is for Suckers PB
Suicide Squad Volume 4 Discipline and Punishments PB
Suicide Squad Volume 5 Walled In PB
Superman Emperor Joker PB
Superman/Batman Vengeance PB
Zatanna the Mistress of Magic PB

A-Force Volume 1 Hypertime
A-Force 1-4, Avengers 0 (A-Force story), Avengers (1963) 83, A-Force (2015) 1
A-Force Volume 2 Rage Against the Dying of the Light
A-Force 5-10
All-New Invaders Volume 1: Gods & Soldiers PB
All-New Invaders 1-5, All-New Marvel Now! Point One (Invaders story)
All-New Invaders Volume 2: Original Sin PB
All-New Invaders 6-10
All-New Invaders Volume 3: The Martians are Coming PB
All-New Invaders 11-15
Amazing Spider-Man Edge of Spiderverse PB
Edge of Spiderverse 1-5
Amazing Spider-Man Renew Your Vows 2015 PB
Amazing Spider-Man: Renew Your Vows 1-5, Spider-Verse (2014) 2 (last story)
Amazing Spider-Man Renew Your Vows Volume 1 PB
Amazing Spider-Man Renew Your Vows 1-6
Amazing Spider-Man by JMS Ulimate Collection 3 PB
Amazing Spider-Man #503-518
Angela Asgard’s Assasin PB
Angela: Asgard’s Assassin 1-6
Avengers Epic Colletion Earth’s Mightest Heroes PB
Avengers (1963) 1-20
Avengers Disassembled Thor PB
Thor 80-85
Avengers/Invaders HC
Avengers/Invaders 1-4
Avengers Standoff! HC
Welcome to Pleasant Hill Prologue 1, Assault on Pleasant Hill Alpha 1, Agents of SHIELD 3-4, Uncanny Avengers 7, All-New, All Different Avengers 7-8, New Avengers 8-10, Captain America: Sam Wilson 7-8, Uncanny Avengers 8, Illuminati 6, Howling Commandos 6, Assault on Pleasant Hill Omega 1
Bucky Barnes Winter Soldier Volume 1 Man on the Wall PB
Bucky Barnes: The Winter Soldier 1-5
Bucky Barnes Winter Soldier Volume 2 PB
Bucky Barnes: The Winter Soldier 6-11
Captain America Civil War Prelude
Captain America vol. 5, #22-24; Winter Soldier: Winter KillsIron Man #13-14; Iron Man/Captain America: Casualties of WarCivil War: The Confession
Captain America Winter Soldier PB
Captain America vol. 5, #1-9, 11-14
Captain America Red Menace PB
Captain America vol. 5, #15-21; Captain America 65th Anniversary Special
Captain America Death of Captain America PB
Captain America vol. 5 #22-42; Winter Soldier : Winter Kills
Captain America Lives! – Marvel Omnibus
Captain America vol. 5, #43-50; Captain America #600-601; Captain America: Reborn #1-6
Captain America The Trial of Captain America – Marvel Omnibus
Captain America: Who Wield the Shield? Captain America (2005) 602-610, Steve Rogers: Super Soldier 1-4, Captain America (2005) 611-619 & Captain America 1-10. 
Captain America Return of the Winter Soldier – Marvel Omnibus
Captain America and Bucky #620-628, Fear Itself #7.1: Captain America, Winter Soldier #1-5, Captain America(2011) #11-19, Winter Soldier #6-14
Captain America & Bucky: The Life Story of Bucky Barnes HC
Captain America and Bucky 620-624
Captain America & Bucky Old Wounds PB
Captain America and Bucky 625-628
Captain America Steve Rogers Volume 1 Hail Hydra PB
Captain America: Steve Rogers 1-6
Captain America Steve Rogers Volume 2 Trial of Maria Hill PB
Captain America: Steve Rogers 7-11
Captain America Steve Rogers Volume 3 Empire Building PB
Captain America: Steve Rogers #12-16, Civil War II: The Oath #1
Civil War PB
Civil War 1-7
Civil War II- Choosing Sides PB
Civil War II: Choosing Sides 1-6
Civil War II HC
Civil War II 0-7
Deadpool Art of War
Deadpool Art of War 1-4 All
Deadpool Daniel Way Complete Collection Volume 1 PB
Wolverine Origins 21-25, Deadpool (2008) 1-12, Thunderbolts 130-131 & Deadpool Saga
Deadpool Daniel Way Complete Collection Volume 2 PB
Deadpool (2008) 13-31
Deadpool Max Nutjob PB
Deadpool Max (2010) 1-6
Deadpool Dead Presidents PB
Deadpool 1-6
Deadpool Soul Hunter PB
Deadpool 7-12
Deadpool V Gambit
Deadpool V Gambit 1-5
Doctor Strange God of Magic PB
Doctor Strange 381-385
Fear Itself PB
Fear Itself : Book of the Skull , Fear Itself 1-7
House of M PB
House of M 1-8
Invaders Now HC
Invaders Now 1-5
Journey into Mystery Complete Collection Volume 1 PB
Journey Into Mystery 622-636, 626.1
Journey into Mystery Complete Collection Volume 2 PB
Exiled 1, New Mutants 42-43, Journey into Mystery 637-645, The Might Thor 18-22 & Annual 1
Loki Agent of Asgard Volume 1 PB
Loki: Agent of Asgard 1-5
Loki Agent of Asgard Volume 2 PB
Loki: Agent of Asgard 6-11
Loki Agent of Asgard Volume 3 PB
Loki: Agent of Asgard 12-17
Mighty Thor Matt Fraction Volume 1
Mighty Thor 1-6
Mighty Thor Volume 1 Thunder in her Veins PB
Mighty Thor 1-5
Mighty Thor Volume 2 Lords of Midgard HC
Mighty Thor 6-12
Mighty Thor Volume 3 The Asgard/Shi’ar War PB
Mighty Thor 13-19
Miss Marvel Volume 1: No Normal PB
Miss Marvel (Vol. 3) 1-5

Miss Marvel Volume 2: Generation Why PB
Miss Marvel (Vol.3) 6-11
Miss Marvel Volume 3: Crushed PB
Miss Marvel (Vol.3) 12-15 & material from Shield 2
Miss Marvel Volume 4: Last Day PB
Miss Marvel (Vol.3) 16-19, material from Amazing Spider-Man vol. 3 7-8
Miss Marvel Volume 5: Super Famous PB
Miss Marvel (Vol.4) 1-6
Miss Marvel Volume 6: Civil War II PB
Miss Marvel (Vol.4) 7-12
Mystique Ultimate Collection Brian McKeever PB
Mystique 14-24
New Avengers Vol. 10: Power PB
New Avengers 48-50 & Secret Invastion Dark Reign
New Avengers Vol. 11: Search for the Sorcerer Supreme PB
New Avengers 51-54
New Avengers Vol. 12: Powerloss PB
New Avengers 55-60
New Avengers: Siege (Volume 13) PB
New Avengers 61-64, New Avengers 3, The List-Avengers & New Avengers Finale
Night of the Living Deadpool PB
Night of the Living Deadpool 1-4 All
Original Sin PB
Point One 1 (Watcher story) & Original Sin 0-8
Original Sin: Thor & Loki 10th Realm PB
Original Sin: Thor & Loki- The Tenth Realm 1-5
Secret Empire Prelude PB
Captain America (2012) 21, 25; Captain America: Sam Wilson 7 (A story), 8; Assault on Pleasant Hill Alpha, Omega; Captain America: Steve Rogers 1-2
Secret Empire HC
Secret Empire 1-10 & Secret Empire Omega 1 
Secret Invasion PB
Secret Invasion 1-8
Secret Wars PB
Secret Wars 1-9
Siege PB
Siege 1-4: The Cabal, Siege Prologue
Sif Journey into Mystery
Sif 1, Journey into Mystery (2011) 646-655
Spider-Gwen Volume 0 Most Wanted PB
Spider-Gwen 1-5
Spider-Gwen Volume 1 Greater Power PB
Spider-Gwen 1-6
Spider-Gwen Volume 2 Weapon of Choice PB
Spider-Gwen 9-13
Spider-Gwen Volume 3 Long-Distance PB
Spider-Gwen 14-15, Annual 1, All New Wolverine Annual 1
Spider-Gwen Volume 4 Predators PB
Spider-Gwen 19-23
Spider-Gwen Volume 5 Gwenom PB
Spider-Gwen 24-28
Spider-Man/Deadpool 0: Don’t Call it a Team Up! PB
Deadpool vol. 2 11, Cable & Deadpool 24, Deadpool vol. 3 19-21, Deadpool vol. 4 10, Deadpool Annual 2
Spider-Man/Deadpool 1: Isn’t it Bromantic? PB
Spider-Man/Deadpool 1-5 & 8
Spider-Man/Deadpool 2: Side Pieces PB
Spider-Man/Deadpool 6-7 & 11-12
Spider-Man/Deadpool 3: Itsy Bitsy PB
Spider-Man/Deadpool 9-10, 13-14, 17-18
Spider-Man/Deadpool 4: Serious Business PB
Spider-Man/Deadpool 19-21
Spider-Man/Deadpool 5: Arms Race PB
Spider-Man/Deadpool 22-26
Spider-Man/Spider-Gwen Sitting in a Tree PB
Spider-Man 12-14 and Spider-Gwen 16-18
Spider-Verse PB
Amazing Spider-Man (2014) 7-15, Superior Spider-Man 32-33, Spider-Verse 1-2, Spider-Verse Team-Up 1-3, Scarlet Spiders 1-3, Spider-Woman (2014) 1-4 & Spider-Man 2099 (2014) 6-8
Tales of Suspense: Hawkeye & Winter Soldier
Tales of Suspense 100-104
The Mighty Captain Marvel: Alien Nation
The Mighty Captain Marvel (2016) 0-5
Thor Volume 1 J. Michael Straczynski PB
Thor 1-6
Thor Volume 2 J. Michael Straczynski PB
Thor 7-12 + 600
Thor Volume 3 J. Michael Straczynski PB
Thor 601-603 & Thor: Defining Moments Giant-Size #1
Thor Ultimate Collection PB
Thor (1966) 604-614, Siege: Loki And New Mutants (2009) 11

Thor & Loki Blood Brothers HC
Loki 1-4, Journey Into Mystery 85 & Journey Into Mystery 112
Thor The Trials of Loki
Loki (2010) 1-4
Thor World Eaters HC
Thor #615-621 & 620.1
Thor Worthy Origins PB
The Unworthy Thor 1-5
Thunderbolts Volume 1 There is no High Road PB
Thunderbolts 1-6
Thunderbolts Volume 2 No Going Back PB
Thunderbolts 7-12
Tsum Tsum Takeover PB
Marvel Tsum Tsum 1-4 All
Unbelievable Gwenpool 1 PB
Unbelieveable Gwenpool 0-4
Unbelievable Gwenpool 2 PB
Unbelievable Gwenpool 5-10
Unbelievable Gwenpool 3 PB
Unbeliaveable Gwenpool 11-15
Unbelievable Gwenpool 4 PB
Unbelievable Gwenpool 16-20
Unbelievable Gwenpool 5 PB
Unbelievable Gwenpool 21-25
Vote Loki PB
Vote Loki 1-4 All
Winter Soldier Bitter March PB
Winter Soldier Bitter March 1-5 All
Winter Soldier Complete Collection PB
Fear Itself 7:1 & Captain America Winter Soldier 1-14
Winter Soldier Electric Ghost PB
Captain America Winter Soldier 15-19
X-Men: Domino
Domino (1997) 1-3, Domino (2003) 1-4, X-Force: Sex & Violence 1-3
Young Avengers: Style > Substance PB
Young Avengers 1-5
Young Avengers 2: Alternative Culture PB
Young Avengers 6-10
Young Avengers 3: Mic-Drop at the end of Time and Space
Young Avengers 11-15
Color Your Own Marvel Tsum Tsum
Color Your Own Thor
Color Your Own Young Marvel
Color Your Own Marvel Civil War

Other Not necessarily by other companies but fall outside normal continuities
Invader Zim Volume 1
Kick-Ass 2 Prelude Hit-Girl
Kick-Ass 2
Kick-Ass 3
Kingsman Secret Service
Once Upon a Time Shadow of the Queen
Pride, Prejudice and Zombies
Snowpiercer 1 The Escape
V for Vendetta