The hero, protagonist, and title character of The Idiot, Myshkin is a descendant of an old noble line and a distant relative of Madame Yepanchin. He is a fair-haired, blue-eyed epileptic in his late twenties who comes to Russia after four years in a sanitarium in Switzerland. From the onset, Myshkin appears to be an outsider in Russian society: he dresses like a foreigner and acts as if unaware of the societal norms of the Russian aristocracy. Indeed, he is different from the other Russian aristocrats in several regards.

First, Myshkin does not follow societal conventions and is not afraid of its sanctions, which mainly come in the form of ridicule. In Part I, he goes to Nastassya Filippovna's even though he has not been invited. He thinks to himself that the worst that could happen would be that the guests would laugh at him and then escort him out. Some of the other characters in the novel, such as Ganya, such shame would be absolutely terrible; for Myshkin, however, it is no big deal. He is not afraid of being laughed at; in fact, when others laugh at him, he joins in with them. When Myshkin first visits the Yepanchins, the girls indirectly call him an ass and then laugh, but he laughs with them.

Furthermore, Myshkin is very open and frank. He tells new acquaintances his personal history—including the bit about living in a sanitarium for several years—right away. He does not believe in societal small talk, instead preferring to immediately jump into a discussion of the issues that are his prime concern. For instance, when Myshkin visits the Yepanchins for the first time, he immediately talks of public executions and the story of Marie. At the "engagement" dinner party at the Yepanchins, he fervently discusses grand subjects such as religion and the future of aristocracy. However, Myshkin's is highly naïve, and he is therefore fooled by members of the high society. He takes their affected friendship for genuine and sincere feeling. Perhaps his innocence is the reason for his special affinity for children. The adult world, however, is too superficial and conventional for him.

Myshkin does not take offense at anyone, no matter how horrific the character's action toward him. After Ganya's slap, Myshkin does not hit back or challenge Ganya to a duel—a common recourse for action at the time. Instead, Myshkin tells Ganya that he should be ashamed of himself and leaves the room. In response to Burdovsky's lie that he is Pavlishchev's son, not only is Myshkin not angry, but he is also still willing to help Burdovsky financially. Even after Keller writes a slanderous and insulting article about Myshkin, the prince still makes Keller the best man at his wedding. Lebedev constantly lies to Myshkin and even tries to commit him to an insane asylum; when Lebedev admits this, Myshkin merely laughs in response. Aglaya constantly mocks and insults the prince, but this only saddens him. When Aglaya expresses any wish for reconciliation, Myshkin is ecstatic with joy. In short, Prince Myshkin does not bear grudges against anyone, even Rogozhin, who almost kills him. In light of Myshkin's seemingly impossible naïveté, virtually all the characters in the novel call him an "idiot."

Prince Myshkin is perhaps the ultimate Christian ideal of humble selflessness and giving. He attempts to help everyone he meets and always holds the needs of others above his own. In the end, he is ready to marry Nastassya Filippovna because he feels it is necessary to save her, even though he is in love with Aglaya instead. Myshkin's compassion toward others knows no boundaries. He is too good for a world corrupted by money, lust, and individual vanity. As a result, he unwittingly adds to the destruction and is destroyed himself.