Having used his vast knowledge to create lasers, giant robots, and the Thousand Sunny's puzzle like architecutre,
1. Benn Beckman. According to Oda's explanation, the right-hand man of Shanks is the smartest human being in One Piece. Not only he excels in fighting, but Benn Beckman is also smart and wise that he can even manage other crews.
Sanji - 120. he s intelligent but not a scientist; Brook - 110.
Given the evidence, Luffy's IQ could easily be anywhere between 90 and 130. This would make his intelligence at least average and maybe a little above average, although not quite genius-level. His morality, choices, actions and accomplishments should say as much about him.
Like his captain, Zoro isn't really intelligent. He's terrible at directions, even getting lost in their own ship, and prefers to just cut his way through. After all, he spent most of his life improving his sword and becoming the strongest swordsman.
Senku Ishigami is believed to possess an IQ of 180 to 200, making him a highly gifted being. He holds a profound knowledge of chemistry, mathematics, physics, biology, and all other subjects. Using his wide sense of knowledge, Senku has proved himself to be the savior of humanity multiple times.
#1 Saiki Kusuo
The smartest character on this entire list, Saiki Kusuo is a step ahead of his jealous brother. Even without the use of his psychic powers, Kusuo would ace any IQ test he took.
Goku: 76, even though you might think his IQ could be even lower sometimes, he often proves he can do some smart things too, especially while fighting and especially during DBZ.
He is loyal and loving towards his friends, demonstrating empathy and a high level of emotional intelligence. Given Luffy's many abilities, it is likely that his IQ is quite high, although it cannot be stated precisely.
115 to 129: Above average or bright. 130 to 144: Moderately gifted. 145 to 159: Highly gifted. 160 to 179: Exceptionally gifted.
Marilyn vos Savant: 228
Born in 1946 in St. Louis, Missouri, Savant was listed as the person with the highest IQ by Guinness World Records.
Pirates in One Piece are not usually renowned for their smarts, yet even with the little that has been seen of Shanks so far, it is clear that he is an extremely insightful individual. It is for this reason that Shanks is usually featured at either the beginning or the end of important events.
Naruto is no exception to this. Of the members of Team Seven, barring Kakashi, we can say that each of them have their own intelligences. As a formality though, the franchise puts Sakura's IQ at 174, Sasuke's at 100 and Naruto's at 90, just below the human average.
Now, without further ado, let's see what Batman's IQ is & how he compares to other smartest characters in both DC and Marvel Universe. Batman's IQ is around 192. This is the most widely cited number, with some sources going as far as to attribute to Batman IQ higher than 210+.
Vegeta-106, About average intelligence and is never shown to have superior intelligence. Piccolo-115, Often portrayed to have clever moments and leads the Z fighters in a smart way. Bulma-190, No surprise Bulma's REALLY smart.
In the comics he has an IQ of over 250. In simplest terms, he's Tony Stark, Reed Richards level intelligent. This is going to be a long answer, mostly scans to prove intelligence. Geoff Johns confirmed that Bruce Wayne is definitively the 2nd smartest person on Earth.
Naruto is definitely the smartest among these three.
1) Shikaku Nara
Shikaku Nara is arguably the smartest character in the Naruto series.
One of the strongest anime characters of all time, Saiki Kusuo had amazing intelligence too. Barring his overpowered psychic abilities with which he could anything, he had a whopping 300+ IQ.