1. Lex Luthor: Often considered the most intelligent human in the DC Universe. He's a brilliant scientist, businessman, and strategist. He's constantly outsmarting Superman and often manipulates world events for his own gain.
2. Brainiac: While not technically a "man," Brainiac is a sentient artificial intelligence from the planet Colu. He's known for his vast knowledge and technological prowess. Brainiac is one of the most dangerous threats in the DC Universe, capable of wiping out entire civilizations with his intellect.
However, there are other characters who could also be considered among the smartest:
* Batman: Bruce Wayne is renowned for his detective skills, strategic thinking, and mastery of multiple disciplines. He's often considered the most intelligent human in the DC Universe, rivaling Lex Luthor.
* The Riddler: A brilliant criminal mastermind with an obsession with riddles. He often outwits Batman through his clever puzzles and schemes.
* Mister Mxyzptlk: A 5th-dimensional imp with nearly infinite power and intelligence. He enjoys playing tricks on Superman, but his intelligence is undeniable.
Ultimately, the ranking of the "smartest" is subjective and depends on how intelligence is defined. It's up to the reader to decide who takes the top spot!