OK, well we’ll all put in our candidates.
King Solomon was the richest and thought to be the wisest man who ever lived. He wrote Proverbs and the Song of Solomon in the Bible. But He himself acknowledged that his riches and wisdom came from the Lord.
So I submit that the smartest, most intelligent person who ever lived is none other than the Living Word of God himself, the Lord Jesus Christ, the Source of all wisdom and intelligence. He made no show of high intelligence, but in fact, as God in human flesh, was the most intelligent man who ever lived. Someday soon, this most intelligent of all men will rule the world as King and Lord. What a day that will be.