On the surface, The Sopranos can look like a simple mafia story, featuring lots of sex and violence and not much else. Fans, however, know that the series was much smarter than many crime dramas. Exploring mental health, generational trauma, and philosophy, the HBO show was full of subtle symbolism and hidden messages. From The Sopranos' premiere back in 1999 to the present, viewers have enjoyed watching and rewatching to find new meanings and interpretations. One mystery, however, remains unsolved decades later and still has fans debating with each other.

In two different episodes of the third season, an unknown man appears on the stairs, standing still in one case and going up with other characters in the other people. In both cases, the figure briefly stands over the shoulder of a main character, seeming to linger ominously. It's unclear who this man is, or even if it's the same man in both episodes,...