Aquaman Mid-Credits Scene Explained
By the end of the movie, we naturally assume he's just had his head stoved in, but the mid-credits scene reveals that he’s actually adrift in the Mediterranean. He's then found by none other than Dr Stephen Shin. If you recognise this name it’s because he’s the hysterical news pundit seen earlier in the film who’s obsessed with this idea of Atlantis being a real thing. Nobody believes him though, despite A) Aquaman, a literal Atlantian, being a celebrity and B) aliens descending on the earth a year prior.
Point B is obviously unconnected to the events of this film but, if that's your reality, fish-men hardly seem a stretch.
After being rescued, Manta awakes in the lab/workroom/hut/whatever of Shin, where the good doctor is piecing together his wrecked suit. Naturally, he's very, very excited about the idea of it being Atlantian technology. For his troubles, he nearly has his face blasted clean off in a moment directly echoing Kane's initial experimentation.
Shin then asks his new friend to tell him how he got it and Manta agrees, so long as he’ll tell him where to find "him". Rising from his bed he throws his grandfather’s knife at a newspaper clipping of... Aquaman.
So, what does this mean? Well first of all the big takeaway is that Manta isn’t dead, obviously, and is still very much coming for Aquaman, also obviously. Thus we can expect him to return for any possible sequels or spin-offs. But the really juicy bit, is that he’ll now probably have genius-level intellect Stephen Shin on his side.
Now Shin is not what you’d consider to be a major supporting character in DC Comics, and in fact only made his first appearance in 2011, but since then he’s worked both for and against Aquaman. There's potential in his backstory for him to play both sides, change allegiances, and plenty of other narrative twists.
In fact in the Comics, he’s actually known Arthur for his entire life so this is already something of a reimagining as it is. Either that, or they just haven’t revealed that element of their backstories yet.
Either way though both Manta and Shin have been ear-marked as potential major players in any follow up movies. However at this juncture, and with reviews currently mixed in the extreme, whether those films materialise remain to be seen.