Death March "Shinka no Mi" isnt strong from the VERY start, but after the first arc he pretty much becomes the strongest and just keeps getting stronger "There Was No Secret Organization to Fight with the World’s Darkness so I Made One (In Exasperation)" technically there is a slow power growth, but since he is the first one to have powers he is effectively the strongest "To Be a Power in the Shadows!" "Tsuki ga Michibiku Isekai Douchuu" "I’m the Evil Lord of an Intergalactic Empire!" Im not sure if this counts, he hasnt really met anyone particularly strong yet "(Um, Sorry) I’ve Been Reincarnated!" "400 Years Old Virgin Demon King" "A Dragon in Slime’s Clothing" "Different World’s Okonomiyaki Chain Store ~Auntie from Osaka, Reborn as Beautiful Swordswoman, on A Mission to Spread Okonomiyaki!~" "Dragon-san Wants a Friend" i havent read far, but she should be an op dragon "Flying Whale’s Wonderful Life – I who has fused with an Invincible Weapon from the Age of Gods will build a city on my back –" I havent read much of this either, but he fuses with an 'invincible' weapon, right? "Ex Strongest Swordsman Longs For Magic In Different World" "From The Strongest Job of Dragon Knight, To The Beginner Job Carrier, Somehow, The Heroes are Depending on Me" "Going Back and Forth Between Earth and The Other World with Space Time Magic"i havent read this one, but from the description looks like what you are looking for "I Said Make My Abilities Average!" "Is the Strongest in Another World a Hero? A Demon Lord? No! it’s a Fairy ~desu!" "My Classmate is 200 Million Years Old" "My Master Disconnected Yet Again" this should be like the epitome of what you are looking for, next to onepunch man "The Daily Life of the Immortal King" this should also be exactly what you are looking for "The Strongest Wingless Gargoyle" ok im tired
the main ones for you are: "My Master Disconnected Yet Again" this should be like the epitome of what you are looking for, next to onepunch man "The Daily Life of the Immortal King" this should also be exactly what you are looking for and i guess onepunch-man
Let's see: Death March Skeleton Knight in Another World Kuma Kuma Kuma Bear Isekai Yururi Kikou Ex-Hero Candidate (not exactly from the start, MC got OP once he hit lv. 2) Legend The New Gate Shikkaku Mon no Saikyou Kenja Magi's Grandson I Said Make My Abilities Average! My Entire Class Was Summoned to Another World except for Me
Honestly there is too many of them and it's a pain to list all of them so here you go choose here~ https://www.novelupdates.com/stag/overpowered-protagonist/
Instant Death Just by saying "die" or if there's someone who wanna kill mc, he can just think and welp, they all dead...
As the Spirit-sama Says Isekai Canceller Isekai de Kojiin wo Hiraitakedo, Nazeka Darehitori Sudatou to Shinai Ken (WN) Levelmaker Kami Sumeragi Yuusha no Eiyuutan 《Ryokou Tan》