During a recent developer update from the Overwatch team, Jeff Kaplan himself mentioned something about the next hero that will be coming to the game. While he didn't disclose a name or really any specifics outside of the character being a male, he did note that the hero won't be arriving anytime soon. Theories have been circulating as of late, but one of the biggest clues comes from the official Twitter for Overwatch World Cup Team Mexico when they tweeted a few images, one of which seems to reveal hero 31.
The images tweeted by Team Mexico are in regards to Role Queue, which was officially revealed recently. The feature is going to essentially overhaul matchmaking by locking players into a 2 tank, 2 DPS, 2 support configuration, with players choosing their roles before even getting into a match. However, in one of the images that shows the overview of a profile, we can see a character that isn't in Overwatch at this time. Sigma appears to be a male, so there is a chance this could be the next hero coming to the game.
⚠️ES OFICIAL⚠️July 18, 2019
El nuevo sistema de Cola de roles ha llegado a Overwatch, llegará tanto a partidas rápidas y competitivas. Se encuentra disponible ya en el RPP.
Of course, there are a few things that are a bit off about the whole situation. As can be seen in the image above, it has "temp art" written on it, indicating it isn't just a screenshot from the game. In addition to this, if Sigma were indeed the next Overwatch hero, who Kaplan said isn't arriving for some time, why would Team Mexico have access to them? Needless to say, there is a good chance that Sigma is fictional and only part of the temp art, so be sure to keep the salt nearby.
During a recent gaming session with former Overwatch League player Brandon "Seagull" Larned, Jeff Kaplan addressed a question about Sigma. "Who is Sigma," Kaplan said. "That's a good question." However, he immediately went on to the next question, opting not to answer. While this could be seen as him keeping quiet about the next hero, it could very well be him wondering who Sigma is himself.
Thanks, Dot Esports.