If you're looking for anime similar to That Time I Got Reincarnated as a Slime, you might like these titles.
On the night his favorite MMORPG is scheduled to be shut down, veteran player Momonga stays logged in until the clock hits zero. The screen goes dark for only a few moments before he finds himself completely immersed in the online world of Yggdrasil. Left with all of his character’s devastating powers, total dominion over his loyal NPCs, and nothing better to do… Momonga decides to try his hand at taking over the world. All the hours he’s spent grinding and dungeon crawling have certainly paid off, and as he tests his strength on local rogues and legendary beasts he comes to realize that not one opponent can stand against his might. Embracing his new identity as the fearsome mage Ainz Ooal Gown, Momonga continues his search for bigger, badder adversaries. Leaving the people of Yggdrasil to wonder who exactly is trapped with who?
Both of these Animes (and mangas) main characters are extremely overpowered compared to other creatures and aren't human. Both of these overpowered creatures rule over others.
Both of them have a MC that is overpowered AF. Both of them were human but are not anymore. Both of the MC rule over others that are also powerful. Although Overlord is a dude going into a game and this is about a guy dying and reincarnating in another world.
After a traffic accident, Kazuma Satou’s disappointingly brief life was supposed to be over, but he wakes up to see a beautiful girl before him. She claims to be a goddess, Aqua, and asks if he would like to go to another world and bring only one thing with him. Kazuma decides to bring the goddess herself, and they are transported to a fantasy world filled with adventure, ruled by a demon king. Now Kazuma only wants to live in peace, but Aqua wants to solve many of this world’s problems, and the demon king will only turn a blind eye for so long…
Both animes are comedy, adventure isekai in a fantasy world. But they are also total opposites that could balance each other quite well.
Both are comedies and isekai. Konosuba pushes more in comedy, Tensei Shitar Slime Datta Ken gives us more fights and super powers.
Sorry for my english im from Poland :)