Robert Oppenheimer

He described himself as the loneliest man in the world.

An excerpt from the article 32 facts about Robert Oppenheimer

Even as a child, he had trouble interacting with his peers. Children thought he was arrogant and taciturn, always with his nose in a book. He shunned people and felt most comfortable interacting with science.

He battled depression throughout his life, once telling his brother, "I need physics more than friends".