Agents of S.H.I.E.L.D. season 6 could feature the return of the Kree. Brought to the big screen through Guardians of the Galaxy and Captain Marvel, the Kree have been a background presence in Agents of S.H.I.E.L.D. since the series began. They were responsible for creating the Inhumans, an evolutionary offshoot of humanity that's featured prominently in the show.
The Kree played a major part in Agents of S.H.I.E.L.D. season 5, with humanity threatened by an alien Confederacy. One of the members of this Confederacy was rogue Kree House Kasius, led by a power-hungry merchant named Taryan. Although the Confederacy was defeated, Taryan was one of season 5's loose ends, now aware of the existence of the Inhumans. With Agents of S.H.I.E.L.D. season 6 heading into space, there'd been intense speculation that the Kree would return.
The evidence is building that those theories could be correct. IMDb lists Christian Ochoa has joined up playing the part of Baal-Gad, slated to appear in at least three episodes. Baal-Gad has no comic book counterpart - the name is Biblical, referring to a Canaanite town in ancient Lebanon - but it follows the traditional Kree hyphenated format. This would suggest the Kree are at least part of a subplot in Agents of S.H.I.E.L.D. season 6.
Meanwhile, the recent Agents of S.H.I.E.L.D. season 6 cast photo has presented a further piece of evidence. The image shows the seven core team members, with Clark Gregg's new character lurking in the background. It's unclear what they're stood in front of, but the most interesting detail is on its surface. Those appear to be Kree glyphs, a form of writing that's been shown in Agents of S.H.I.E.L.D. since season 2. It suggests that the mysterious alien environment - which is of a Kree-typical purple color scheme - is tied somehow to the Kree.
Agents of S.H.I.E.L.D. has always had to strike a careful balance. On the one hand, the show has always striven to establish its own mythology in the MCU, expanding the wider cinematic universe. At the same time, though, it's often been held in check because the greatest developments need to happen on the big screen in the Marvel movies. That's meant the series has had to build up the Kree gradually, for fear of contradicting anything. Now that Captain Marvel has finally been released, though, the Kree are now much more a known commodity. Agents of S.H.I.E.L.D. doesn't need to be so wary anymore; it can potentially dive into Kree society like never before.