If you started from beginning, you know that comics are excellent reading material, because with just a few words (and a lots of pictures) you can advance story and have fun.
There are many online resources, my favorite is Read Comics Online - it has thousands of comics of many types. Sometimes website asks you to solve a puzzle before loading the page: click on images of cars, street signs and similar. If you are not sure, click "reload" to request different puzzle.
Best way is to start reading some story you know in your own language.
Cartoons based on movies you likely know (or can watch before reading comics) for kids: Monsters Inc (and 2), Incredibles, Toy story, Cars; for adults: Mission Impossible, Men in Black (and 2, 3 and prequel), 300 (Spartans), Jurassic Park (and 2), Terminator (and 2 and few more), Django Unchained, King Kong (and 2), Highlander, (and many more), Stargate, Game of Thrones or sci-fi classics like Blade Runner (exact movie), 2001: Space Odyssey, Planet of the Apes, Stargate, Indiana Jones
Cartoons based on books for young children: Classic stories for children, Fairy Tales, Alice in Wonderland (and another, also as steampunk), Smurfs, Wonderful Wizard of Oz and for older children 1001 Arabian Nights and another, Sinbad, Alladin,
Educational comics like Cartoon History of the Universe (highly recommended), American Revolution (and more)
Comics about life of real persons like Fifth Beatle, Martin Luther, Death of Stalin, Rasputin, Battlefields: Night Witches (Russian night female pilots in WW2), Korean War, Napoleon's wars (drawn with incredible eye for detail), 47 Ronin ("story to know Japan"), or real places and times like life of immigrants in NY and Bronx in 1930, Jerusalem and Palestine, growing up in Tehran during Islamic Revolution, March to end segregation in USA, or North Korea (comic can show what documentary cannot).
Stories based on books: Three musketeers, Treasure Island, Last of the Mohicans, Dracula, Frankenstein (and retelling), Sherlock Holmes, Edgar Alan Poe stories, Moby Dick, Terry Pratchett's The Colour Of Magic
Children stories retold for adults, with sex and violence: Grimm Fairy Tales and Red Riding Hood as Japanese warrior and Founding Fathers of America as action heroes
Books for adults: Girl with Dragon Tattoo, who played with fire when kicked the hornet's nest; Pride and Prejudice,
Alternative history (what if something in history happened differently) is popular: What if USA lost Operation Paperclip (arresting German rocket scientists) so UK developed space flight? What if Germans in WW2 developed enhanced humans (ubermen) and invaded USA (which is very well researched: did you know that it took full month to create enough plutonium for single "fat man" bomb, and year for uranium "little boy" bomb)?
Of course classic science-fiction are present: H. G. Wells' The War of the Worlds, Dune, Ender's Game: Battle School, Command School and prequel Mazer Rackham, and more brilliant sci-fi: Forever War, Rock and Stone, Mercury Heat
Whole cult series like Watchmen (with prequels for each superhero in Before Watchmen series).
Star Wars, Star Trek have huge following. There is whole alphabet of action heroes: Aliens, Batman, Conan the Barbarian all the way to Zorro (Predator, Transformers, Superman, Spider-man, , Ninja Turtles, Tarzan (and Jungle girl), James Bond, Hulk, Iron-man,) all have dozens of comics each - use search. And combinations: Batman vs Predator, Terminator vs Robocop, and so on.
If you are interested in Vikings, there are whole series. I really liked Valhalla, which explains different gods (like unexpected side of Freyja, godess of love in #8). And other popular Nordic gods like Thor (and 2, 3), Loki (and 2, 3), Sif, fighting in Ragnarok or in present, or historic Viking invasion.
Greek Mythology like Trojan War (and another), Odyssey, Minotaur, Oracle.
History of Roman Empire like Eagles of Rome, Britannia, Druids, Caligula, Murena
Wild West heroes like Jonah Hex, Lucky Luke (and another)
Cartoons for popular table games like Magic: The Gathering, Dungeons and Dragons and video games like Tomb Raider
Or just intelligent fun in short strips, like Calvin and Hobbes (boy with his stuffed tiger).
And surprise (or not): Bible and Bible Tales, Life of Christ and of course action heros: Jesus Christ: Demon Slayer and Klaus (Before becoming Santa).
