Satoru Mikami, a salaryman, was reincarnated in a different world when he noticed. However, its appearance was slime. The main character Rimuru is powerful as hell.

Ainz Ooal Gown

A lonely boy who likes games becomes the strongest wizard in the real  world, leading the guild and confronting another world It’s a dark  fantasy that depicts how it goes. 

Sadao Maou

It is a popular fantasy, the Demon King who works as a part-time  worker while being caught in the rough waves of the Japanese economy. The main character is a overpowered Demon King.

Rudeus Greyrat 

It about a 34-year-old virgin and unemployed man who died a tragic death and reincarnate into a magical world as a baby. He is a very special child who learn magic and become op.

Every year tons of isekai anime is released, but not all have OP characters.