Afghanistan

Dust, Sedara Bakut (Psi-Force)

Albania

Michael Fondozzi

Algeria

Emplate, M, Nicole and Claudette St. Croix

(M has Citizenships in Bosnia, Algeria, and France)

Argentina

Black Tarantula,Defensor , Saint Anna

Armenia

Annie Ghazikhanian, Carter Ghazikhanian

Atlanteans

Atlantis

Andromeda, Attuma, Bloodtide, Byrrah, Dorma, Dragonrider, Krang, Llyra, Manowar, Meranno, Namor, Namora, Namorita, Nia Noble, Sea Leopard, Tyrak, Varnae

Australia

Barnacle, Bonebreaker, Boomerang, Boomslang, Dreamguard, Ever, Gateway, Grizzly (Theodore Winchester), Gorgeous George, Jack-in-the-Box, Kangaroo (Frank Oliver), Key & Wall (mutants), Lifeguard, Angelo Macon, Pyro, Murray Reese, Skullbuster, Slayback, Slipstream, Talisman (Contest of Champions)

(Slayback has citizenships in Canada and Australia)

Austria

Destiny, Doctor Faustos, Mystique (most likely), Ringmaster (Maynard Tiboldt)

Azania

Barricade, Captain Blaze, Harrier, Hungyr, Voortrekker, White Avenger

Bahamas

Blink

Belarus

Darkstar, Presence, Vanguard

Belgium

Belgian Brain, Mr. M, Rem-Ram

Brazil

Captain Forsa, Magma (Amara Aquilla), Reignfire, Sunspot

Bosnia

M

(M has Citizenships in Bosnia, Algeria, and France)

Cambodia

Angkor, Midnight’s Fire, Silhouette, Tai

Canadian heroes

Canada

Aurora, Ajax (Francis), Box (Roger Bochs), Sam Buchanan, Centennial, Cyber, Daydreamer, Deadly Ernest, Deadpool, Diamond Lil, Director (Malcolm Colcord), Double Trouble, Earthmover, Flashback, Flex, Ghost Girl, Gilded Lily, Goblyn, Graviton, Grizzly (Maxwell Markham), Groundhog, Guardian (James Hudson), Heather Hudson (Exiles), Hunter in Darkness, Iceboy (Euroforce), Jerome Jackson, Madison Jeffries, Garrison Kane, Killspree, Living Totem, Major Mapleleaf, Manbot, Manikin, Murmur (Arlette Truffaut), Nemesis (Jane St. Ives), Nemesis (Amelia Weatherly), Night Raven, Northstar, Persuasion, Pink Pearl, Puck, Radius, Sasquatch, Shaman(Michael Twoyoungmen), Silver Fox, Sinew, Slayback, Smart Alec, Snowbird, Squidboy, Stitch, Talisman (Elizabeth Twoyoungmen), Tigerstryke, Vindicator (Heather MacNeil Hudson), Wendigo (most often), Wolverine, Witchfire, Wyre, Zuzha Yu, Yeti, Yukon Jack

(Slayback has citizenships in Canada and Australia)

Carpasia

Scorpio (Mikel Fury)

China

Abomination (Chang Lam), Auric, Cerebra,China Force (Snake, Rabbit, Ox, Rat, Dog, Horse, Monkey), Collective Man, Crimson Dynamo (Alex Su), Cursed Lotus, Doctor Sun, Tsin Hark, Fu Manchu, Jade Dragon, Ladykiller, Lionmane, Mandarin, Mandarin's Avatars, Moving Shadow, Nuwa, Pao Fu, Radioactive Man, Red Lotus, Saul, Shang-Chi, Silver, Lin Sun, Sway, Temugin, Kuan-Yin Xorn, Shen Xorn, Yellow Claw

Colombia

Highnote

Costa Verde

Silverclaw

Croatia

Abomination (Emil Blonsky), Purple Man

Cuba

Hope, La Bandera, Armena Ortega, Poison (Cecelia Cardinale), Risque

Denmark

Petra

Egypt

Akhenaten, Amun, Apocalypse, Ashake, Asp, Baal, Holocaust, Rama Kaliph, Lion God, Living Monolith, Living Mummy, Mad Pharaoh, Nephrus, Ozymandias, Ramades, Scarlet Scarab (Abdul Faoul), Scarlet Scarab (Mehemet Faoul), Shadow King, Sphinx (Meryet Karim), Sphinx (Anath-Na Mut)

British heroes

England

AC-DC, Albion (Peter Hunter), Alchemy, Amergin, Argent, Baron Blood (Kenneth Crichton), Baron Blood (John Falsworth), Baroness Blood, Bela, Astrid Bloom, Blackheath (Plantman), Black Knight (Nathan Garrett), Black Knight (Percy of Scandia), Blade, Bloodscream, Elsa Bloodstone, Sir James Braddock, Jamie Braddock, Breeze, Godfrey Calthrop, Captain Britain (Brian Braddock), Captain Kerosene, Captain Midlands, Captain UK, Captain Wings, Decibel, Lila Cheney, Citizen V, Constance Johanssen, Crimson Crusader, Algernon Crowe, Adam Crown, Cuckoo, Dark Angel, Adam Destine, Deep Sight (EuroForce), Destroyer (Roger Aubrey), Digitek, Doctor Synne, Alison Double, Excaliber (Jason Struthers), Fantomex, Ben Gallagher, Garokk, Ghost Girl, Gilded Lily, Fransesca Lexley Grace, Bronwen Gryffn, Ranulph Haldane, Edwin Jarvis, Justin Hammer, Quincy Harker, Hex, High Evolutionary, Highwayman, Ned Horrocks, Henrietta Hunter, Huntsman (Weapon XII), Hurricane (Albert Potter), Immortalis, Imp, Jack the Ripper, Breeze James, Ka-Zar, Solomon Kane, Killpower, Knight Templar, Morgana LeFey, Tom Lennox, Tommy Lightning, Lionheart, Mad Jim Jaspers, Kate McClellan, Meggan, Merlin, Micromax, Modred the Mystic, Mordred, Motormouth, Mountjoy, Oonagh Mullarkey, Outlaw (Nigel Higgins), Oxford Blue, King Arthur Pendragon, Plasmer, Plunderer, Porlock, Psylocke, Rathcoole, Reaver (Joshua Stragg), Clive Reston, Tom Rosetta, Courtney Ross, Lord Ruthven, Opal Luna Saturnyne, Sat-Yr-9, Scarlet Knight, Scicluna, Shockwave, Morgan Sinclair, Mr. Sinister, Frederick Slade, Hamilton Slade, Slaymaster, Jack Starsmore, Victor Sternwood, Alistaire Stuart, Alysande Stuart, Amina Synge, Spider-Woman (Jessica Drew), Spitfire (Jacqueline Falsworth Crichton), Amina Synge, Dai Thomas, Thunderclap, Thunderfist, Toad, Warren Traveler, Gudrun Tyburne, Ultimaton, Union Jack (Joseph Chapman), Union Jack (Brian Falsworth), Rachel van Helsing, Vixen, Wallop, Windshear, Pete Wisdom, Romany Wisdom, Ormond Wychwood

Ethiopia

Moses Magnum

Equador

Doghead

Finland

Javelin (Super Heroes of Europe)

Les Heroes de Paris

France

Adamantine, Elsa Ames, Batroc the Leaper, Bevatron, Bloodline, Chain Lightning, Chevalier Bretagne, Commanda, Comte de Nuit, Crimson Cavalier, Cyclone (André Gerard), Cyclone (Pierre Fresson), Détective Fantôme, Diadem, Docteur Q, Ecstasy, Exodus, Flambé, Frenchie (Jean-Paul Duchamp), Frog-Man (Francois Le Blanc), Gargouille, Garrote, Grey Gargoyle, La Lumière Bleue, La Nuit, La Voisin, Lancelot, Le Cowboy, Le Vent, Mandala, Martyr (Yvette Diamonde), Mauvais, Nuage,Peregrine , Princess Python , Prism, Radion (Henri Sorel), Rapido, Schizoid Man (Ultimate universe), She-Wolf, Swordsman (Jaques DuQuesne), Margali Szardos, Tarot, Tempest (Nicolette Giroux), Tiger (Hughes Ait Kaci), Time Bomb, Tricolore

Genosha

Abyss, Chimere, Freakshow, Genegineer, Hack, Hawkshaw, Hub, Shola Inkosi, Renee Majcomb, Phillip Moreau, Negasonic Teenage Warhead, Piecemeal, Pipeline, Pirouette, Prodigal, Punchout, Purge, Sasha Ryan, Jenny Ransome, Wicked, Wipeout, Zealot

Germany

Achilles (Helmut Halfing), Agent Axis (Berthold Volker), Agent of 1000 faces, Armless Tiger Man, Baron Zemo (All), Baroness Zemo, Baron von Blitzschlag, Black Swan, Blitzkrieger, The Brain, Brain Drain, Bulwark, Captain Axis, Cobra (Dietmar Stock), Courier, Crule, Dachs (Patrick Kurz), Frankenstein's Monster, Deacon Frost, Der Gotteskrieger, Geist, General Skul, Hate-Monger (Adolf Hitler), Hauptmann Englande, Iron Cross, Isolationist, Key (EuroForce), Erik Koenig, Libra (Gustav Brandt), Man-Killer, Masked Raider (Dirk Mehler), Master Man, Maverick (Cristoph Nord), Nightcrawler, Planner, Python (Emil Cullen), Red Skull (Johann Schmidt), Ringmaster (Fritz Tiboldt), Saberbat, Saint George, Amanda Sefton, Skyshark, Stonecold, Andrea von Strucker, Andreas von Strucker (Swordsman), Elsbeth von Strucker, Wolfgang von Strucker, Swarm, Vormund (Hauptmann Deutschland), Wall, Warrior Woman, Watchlord, Zyklon

Ghudaza

Achebe

Greece

Avalanche, Carnivore (Andreas Zorba), Elektra, Hercules, Mordecai Midas, Minotaur, Morbius, Odysseus, Oracle (Super Heroes of Europe), Sage, Sersi, Thena

Chris Claremont has stated that Sage is greek, but it hasn't been confirmed in a comic yet.

Many of the Olympian gods has greek citizenships

Greenland/Inuit

Harpoon, Ice Princess, Moonstalker, Sedna

Guatemala

Ojo Macambra

Haiti

Brother Voodoo, Calypso, Marie Laveau

Halwan

Scimitar

Hong Kong

Cat (Shen Kuei), Cybermancer, Kogar, Ao Jun, Paradigm, Shadow Slasher, Leiko Wu

(Leiko Wu has citizenships in China, England and Hong Kong)

Hungary

Elizabeth Bathory, Blizzard (Gregor Shapanka), Dimensional Man, Marcus Tsung, Viper, Zofia (Wife of Dracula)

S.H.E. - Super Heroes of Europe

Iceland

Strongman (Super Heroes of Europe)

India

Agni, Black Box, Calculus, Haven, Indra (Paras Gavaskar), Monsoon, Omega Sentinel (Karima Shapandar), Rajah, Kavita Rao, Neal Shaara, Adri & Taj Nital, Serpent, Spider-Man (Pavitr Prabhakar), Star Thief, Timeslip, Topaz (possibly), Vindaloo

Iran

Abdul al-Rahman (Ultimate universe) Hassan ibn-Sabbah

Iraq

Aminedi, Blind Ali, Gilgamesh, Saladin, Sirocco, Veil

Ireland

Banshee, Black Tom Cassidy, Bloodwraith, Boulder, Conquest (Bridget Malone), Dyke, Feron, Highlander, Mellencamp, Plasma (Leila O'Toole), Maureen Raven, Rapscallion, Sea Witch, Shamrock (Molly Fitzgerald), Shamrock (Super Heroes of Europe), Siryn, Stealth (Carlos McNally), Teleplex, Wee One

Israel

Arabian Knight (Navid Hasim), Astra (Brotherhood), Brightsword, Catalyst, Gabrielle Haller, Legion, Sabra, Wild Rose

Arabian Knight (Navid Hasim) was born in Israel but is a citizen of Saudi Arabia

Italy

Argento (EuroForce), Belasco, Lucrezia Borgia, Cagliostro, Captain Italy (Ultimate universe), Contessa Valentina Allegra de la Fontaine, Count Nefaria, Marco Delgado, Great Gambonnos, Madame Masque, Milan, Victoria Montesi, Vittorio Montesi, Saracen, Silvermane, Stigmata, Suspiria, Tyrannus, Unus, Unuscione

Jamaica

Hairbag, Shift (Clifton Joseph)

Japanese heroes

Japan

Amiko, Anthro, Armor (Hisako Ichiki), Base (Hiro Sokuto), Cybertooth, Deadline, Decay (Yoshiro Hachiman), Ebon Samurai, Go-Devil, Gogo Tomago, Gorgon (Tomi Shishido), Hachiman, Harvest (Chi Lo), Seiji Honda, Honey Lemon, Irezumi, Kamikaze, Kimura, Kirigi, Amiko Kobayashi, Kuroko the Dark One, Kwannon, Lady Deathstrike, Lady Lotus, Lord Darkwind, Mace (Shigeru Izaki), Miz Tree, Nightmask (Izanami Randall), Ogun, Otomo, Samurai Steel, Kono Sanada, Silver Samurai, Snapdragon, Steel Vengeance, Steel Wind, Sumo, Sunfire - Exiles (Mariko Yashida), Sunfire (Shiro Yashida), Sunpyre, Surge (Noriko Ashida), Hiro Takachiho, Opal Tanaka, Tattoo (Tudo Sokuto), Timestream, Matsuo Tsurayaba, Colleen Wing, Wiz Kid, White Ninja, Mariko Yashida, Shingen Yashida, Yukio

Kenya

Ainet, Bedlam (Olisa Kabaki), Kidogo, Storm

Korea

Chance (Fallen Angels), Desert Ghost, Dragonfly (Meiko Yin), Hurricane (Ultimate universe), Scrambler, Jin Taiko, Angela Yin

Kuwait

Anubis (Ahmad Azis)

Latveria

Doctor Doom, Dreadknight, Dimitri Fotunov, Vladimir Fortunov, Geldoff (Ultimate), Mengo Brothers, Pandemonia, Psi-Borg, Kristoff Vernard

Lemuria

Llyron, Naga, Nagala

Lithuania

Crucible

Macedonia

Cleopatra

Madripoor

Aardwolf, Carmilla Black, Chimera, Dragonwing, Dragoness, Jet-Black, Nightwind, Sapphire Styx, The Sign, Spoilsport, Tough Love

Malaysia

Anaïs

Malta

Don Fortunato

Mbangawi

Doctor Crocodile

Mexico

Arclight, Brimstone Love, Cheetah (Esteban Carracus), Cuauhtli, El Aguila (Paco Montoya), El Muerto, La Lunatica, Carlos Lobo, Rictor, Riptide

Morocco

Jetstream

Netherlands

Beak (?), Cobra (Klaus Voorhees), Flying Dutchman's Ghost, Abraham van Helsing, Klaw, Snow Queen, Spiderman (Hans Jansen)

New Zealand

Greystone, Morgain Kain, Kiwi Black, Tuatara

Norway

Harald Jaekelsson

North Ireland

Liam Connaughton

Pakistan

Omar Karindu, Taboo

Peru

Arachne (Sylvie Yacqua), Inza, El Toro Rojo

Poland

Bloodlust, Golem (Jacob Goldstein), Magneto, Rattler

Poynesia

Varua

Puerto Rico

Bantam (Roberto Velasquez), Fer-de-Lance, Cecilia Reyes, Miguel Reyes, Tag, White Tiger (Hector Ayala)

Romania/Transylvania

Absynthia, Baron Mordo, Bloodbath, Lilia Calderu, Zoe Culloden, Lilith Dracul, Dracula, Gypsy Moth, Astrid Mordo, Nimrod (Vampire), Ludwig VanDoom, Werewolf by Night

Bogatyri - Russian Heroes

Russia

Airstrike (Dmitri Bukharin), Baba Yaga, Black Death (Ivan Kivelki), Black Widow (Natasha Romanoff), Blind Faith, Bora, Chameleon, Colossus (Piotr Rasputin), Concussion, Crimson Dynamo, Dark Angel (Mia Lessing), Devastator, Doctor Volkh, Dragunov, Epsilon Red, Fantasia, Firefox, Gargoyle (Yuri Topolov), Ghost-Maker, Mikula Golubev, Gremlin, Grim Hunter, Hammer (Boris Lubov), Anastasia Inyushin (Psi-Force), Iron Curtain, Iron Maiden (Melina Vostokoff), Katu, Kraven (Sergei Kravinoff), Debra Levin, Aleksander Lukin, Madame X, Magik (Illyana Rasputin), Mindwolf, Mindsinger, Morning Star, Omega Red, Ivan Pushkin, Ransome Sole, Mikhail Rasputin, Red Flag, Red Guardian (Alexi Shostakov), Red Skull (Albert Malik), Rhino, Russian, Scattershot, Seraph, Sibercat, Sickle (Nickolai Vronsky), Gregor Smerdyakov, Soul Skinner, Starlight (Tania Belinskaya), Steel Guardian, Stencil, Synthesizer, Syvatogor, Titanium Man (Boris Bullski), Ursa Major, Alexi Vazhin

Samoa

Mondo

Saudi Arabia

Abdul Ahazred, Arabian Knight (Navid Hasim), Arabian Knight (Abdul Qamar)

Savage Land

Amphibius, Avian, Barbarus, Brain Child, Equilibrius, Gaza, Leash, Lorelei (Brotherhood), Lupa, Lupo, Nereel, Piper, Vertigo, Whiteout, Worm

Scotland

Aberdeen Angus, Ahab, Bible John, Black Axe, Clansman, Claymore, Kylun, Lady Daemon, Ocelot, Proteus, Spoor, Joseph MacTaggert, Moira MacTaggert, Wild Child, Wolfsbane, Zaran

Singapore

Crawler, Slider, Leiko Tan

Slovakia

Unicorn (Milos Masaryk)

Slorenia

Ember, Locomotive Breath, Volkhvy

Somalia

Lightbright

South Africa

Maggott, Patrick Slade

Spain

Aguila (Alejandro Montoya), Brass Bishop, Captain Spain (Ultimate universe), Conquistador, Diablo, Empath, Fire-Eater, Gideon, Matador, Picaro (EuroForce), Static, Vargas

Sweden

Ankhi, Beowulf, Bruto the Strongman, Magma (Super Heroes of Europe)

Switzerland

Flag-Smasher, Victor Frankenstein, Erik Kleinstock, Sven and Harlan Kleinstock, Madam La Farge, Neophyte, White Cross, Arnim Zola

Symkaria

Silver Sable

Syria

Al-Adil, Batal, Swarm (Ultimate universe)

Tahiti

Pele

Thailand

Stonecutter, Tyger Tiger

Tibet

Ancient One

Transia

Bova, The Knights of Wundagore, Man-Beast, Mongoose, Puppet Master, Quicksilver, Rakkus, Scarlet Witch

Turkey

Turham Barim, Flying Carpet, Elianne Turac

Uganda

Riek Bukenya

Ukraine

Amazon (Super Heroes of Europe), Black Widow (Yelena Belova)

Venezuela

Wind Dancer

Vietnam

Bengal, Brother Power, Karma, Leong Manh, Nga Manh, Mantis, Quicksand, Razorblade, Rolling Thunder, Sha Shan, Silk Fever, Sister Sun, Smiling Tiger

African heroes

Vorozheika

Druig

Wakanda

Afrikaa, Black Panther (T'Chaka), Black Panther (T'Challa), Coal Tiger (Earth-982), Gentle (Nezhno Aminedi), Jakarra, Derek Khanata, Erik Killmonger, Malice (Nakia), Man-Ape, Sawadi, Solomon Prey, Vibraxas, Vibraxis

Wales                

Captain Cymru, Pixie (Megan Gwynn), Red Dragon (Super Heroes of Europe), Stinger (Genetix), Damian Tryp

Zaire             

Shanna              

Zambia                

Impala              

Zanzibar                

Askari