First, a note on release timing. Characters are released one at a time, so don't ever expect to see multiple at once unless something strange goes on.
Now, onto the new Overwatch heroes. Remember that some of this is guesswork, rumour-milling and hint-mongering at the best of times, so not all of these will resolve into heroes, if at all - where things are unlikely, we’ll let you know. We're not expecting to ever see something as mad and long-lasting as the Sombra ARG again, but never say never.
When will hero 27 show up? We're not far out from Moira's announcement yet, so don't expect it any time soon. BlizzCon will be the last set of major announcements from big blue during 2017, so you'll be waiting for a press event some time in 2018 for the next big reveal. Overwatch League starts on January 10, but that would also seem pretty early to get a new hero. However, the beginning of Stage Two in late February/early March fits perfectly with the timing seen around Orisa's tease and release. That would be our bet.
We will eventually hit a point where Blizzard won't want to add more heroes to the game, as they've said that the hundreds of characters in MOBAs isn't the right fit for the game. However, we're likely looking another couple of years down the line before that is the case - around the 35-40 mark.
Athena - Support AI
Athena isn’t actually a new character, she’s been in the game since the very first days of the beta. Taking the same role as the Administrator in Team Fortress 2, Athena is Overwatch’s announcer - letting you know when you’re about to get into battle, win, lose, or kill entire teams.
In the lore, she’s the AI that helps to run Overwatch as an organisation, specifically assisting Winston in the creation of his scientific marvels and in restarting Overwatch in the Recall cinematic. She almost gets hacked by Reaper, but manages to reboot before he can finish.
The reason people believe she’ll become a character is twofold. First is that she's already a massive part of the game’s backstory and fits into a support role. She’d be a very natural addition to the cast and one that people want - effort and passion Blizzard won’t want to waste.
The second reason comes down to concept art and pre-release evidence. It’s been theorised that the various full cast shots released for the game over the years, before the first roster of 21 heroes was locked in, already showed her off. A cyclops omnic was in one shot, in the foreground just enough that it would suggest Blizzard were confident they would make it in. It also featured a very similar logo on its forehead to the Athena one seen in-game.
We asked Blizzard directly about Athena during an interview, but they had nothing to say about where she was going - not at launch, anyway. This robot bares a striking resemblance to Iris, one of the pre-launch heroes shown during the BlizzCon 2017 archives panel. While that doesn't mean we definitely won't be seeing Athena, it does seem unlikely it would be in a similar form to one they were so willing to show in a throwaway image.
Jeff Kaplan's DICE 2017 talk had this image of some hero silhouettes, and look who showed up:
She's also appeared in a huge amount of concept art over the years - but unlike Spider Tank, continues to appear in newer pieces, like the above.
Recluse, aka Spider Tank - Unknown
The image above is a very old piece of concept art for Overwatch, which we finally got a decent look at during Jeff Kaplan's DICE talk in early 2017. In the centre is a strange half-spider, half-woman, laser-spewing baddie who remains the only unidentifiable hero in the piece.
Exactly who or what 'she' is hasn't been confirmed, though Blizzard have dodged any questions about her so far. This old Overwatch art also popped up again in Kaplan's talk:
The woman with the purple wings at the back, previously thought to be an old design for Pharah, is the same hero, her legs seemingly unfolding from there. Bastion has multiple forms, so perhaps this is another hero with multiple configurations. Here's a close-up:
To calm our bonfire a tad, both pieces of art are from as early as 2014, with the second clearly depicting an Overwatch that was far edgier than the version that came to life. Many recognisable characters can be seen there, but equally loads have been totally changed since this time. She also showed up as 'Recluse' during the Overwatch Archives panel at BlizzCon 2017.
A lot of the hype for her also came due to confusions between leaked Orisa descriptions and the timing of Kaplan's DICE talk. Mega-rad as she is, it's possible she hasn't been a part of the cast for a long, long time. With such a massive presence in the battlescape art and her odd aesthetic, it would also be understandable if she was more of an NPC boss than a playable character.
The Junkertown Queen - Unknown
Revealed as part of the Junkertown cinematic short and present in a picture on the map itself, the officially un-named character that rules over Junkrat and Roadhog's hometown was an immediate community favourite. Here's the only picture there is of her:
Arguments against it being any time soon are many - she was clearly never intended to get the community so super-interested in this way. She'd also be the third character from the same place, and beyond a bit of voice acting in the Junkertown trailer she's not exactly fleshed out.
But, community demand affects every game and there's a lot for the Queen. It may be a long way down the road but we'll probably see her - eventually.
Liao And Another - Unknown, one possibly a tank
The most likely hinted at hero, and the one with the least amount of info out there, is Liao. They were a founding member of Overwatch along with Soldier: 76, Ana Amari, and Reaper, among others. We have nothing but a name, sourced from an in-universe post about the organisation itself, and nothing beyond that is even hinted at. In Ana's lore trailer, we did see this image of the full old Overwatch crew:
It's possible that Liao could be either of the unrecognised characters on the outer edges. Based on the Asian-sounding name, I'd go for the fella myself, leaving the armoured woman as another new character. Given she looks like a complete and total badass, I'd bet on her being the tank, something hinted at by the numbers of each class in-game, plus some comments from Blizzard.
Alejandra - Unknown
This is much more of a guess, but one the community has built up a lot of evidence for. Alejandra and her mother feature in the Soldier: 76 animated short Hero. With the focus put on this character - even more so than Soldier himself, despite the latter actually featuring in the game already - many felt it was a hint towards a future hero. Some even pointed to Alejandra and Sombra being the same character, due to both having a connection to the Dorado map. While that doesn't seem to be true (though who knows with Sombra's unreliable tales of her own past), Alejandra's significance hasn't been downgraded in the minds of some.
The main issue here is timelines, though Overwatch's is rather confused as it is. Alejandra's age is never verified, or when the cinematic short takes place, but the youngest current character is D.Va at 19 - it seems unlikely Blizzard would want to go much younger than that. Of course, having a future version of a character isn't exactly out of the realms of believability either. Her mother, on the other hand, would dodge that, though is given significantly less characterisation in Hero.
If Alejandra is an upcoming hero, she's probably a ways off - others have been built up much more, and there are less-finished storylines that still need to play out. Her voice actress, Brigitte Kali, said on Twitter during the Sombra hype that she "couldn't say much" about future plans with Blizzard. At the time people thought that confirmed suspicions as to who Alejandra grew up into, but Sombra's voice actress is Carolina Ravassa. If she wasn't just teasing, it does mean we'll see more of her, eventually.
Others - Various
Then there are the characters that could become full-fleshed heroes, but there isn't strong evidence that they will. These are mostly minor characters from maps, comics or animated shorts. Rather than listing every single character in the Overwatch expanded universe, we've cut it down to ones that have a significant enough impact on the world or focus put on them that it's believable they might make the jump eventually.
- Timmy & Brian - these are the two kids from the original cinematic trailer. They would probably need to grow up quite a bit first, though both have proved popular with the fanbase and are currently in-game as sprays.
- Rosa - a child character in Symmetra's comic who has her face burned badly by the Vishkar Corporation's violent machinations. She gets just enough screentime to possibly be a future hint.
- Sound Quake - Mentioned by Timmy in the first cinematic trailer as using chest missiles, Sound Quake was a villain earlier in the game's storyline, fighting against the original Overwatch team.
- Sven - the villain in Torbjörn's comic who survives their fight. With Overwatch's need for villains, and him and Torb clearly having history, it's a distinct possibility we'll see more of Sven in the future.
- Brigitte - Reinhardt's assistant and armour-builder, as well as friend, she's one of the more fully developed comic-only characters, making it seem likely she'll pop up again. She showed up again in the Reinhardt animated short and instantly garnered a whole load more fans, as well as having her identity as Torbjorn's daughter revealed.
- Hakim - the unseen bad guy of Ana's second comic who had been hunting her down. Based on Reaper's dialogue, it's a high-ranking member of the Talon organisation who are in desperate need of some more people in-game.
- Gabrielle Adawe - The secretary-general of the UN during the start of the Omnic Crisis who set up Overwatch and is mentioned in one of the pre-release in-universe articles. Given most of the old Overwatch team has made it to the game, and the rest are heavily hinted at, Gabrielle could also make it.
- 'Greek' - A leak by a Greek voice actor had the community going mad about the possibility of an Ilios-based hero. However, he released a statement saying that it was for background characters. More likely, this suggests an upcoming short is set on the map or in the country.
That’s everyone Blizzard seem to have under the hood for now - more details on them, as well as the squads of heroes coming afterwards, in the near future.