We are talking about the pre-Sophie Turner Jean Grey and the Mad Queen Daenerys Targaryen. 

Both Daenerys and Jean Grey started off as heroes, trying to make the world a better place. 

Admittedly, Dany’s arc has always revolved around her wanting the Iron Throne, but she had always stood up for the marginalised because at the beginning of the show, she was one of them. 

In the first X-Men film, we see Jean testifying in front of the American Congress that wanted to mark all mutants. Being a mutant herself, she understood the plight of her fellow men and women and strictly protested racial profiling.

Both Daenerys and Jean Grey murdered the men they loved. 

Although, Dany killing Khal Drogo was an act of mercy more than anything else, but she did kill him. 

Jean Grey, after returning to life with the Phoenix forced, unleashed it on Scott Summers(Cyclops) and disintegrated him. 

Daenerys was sought after by powerful men in the 7 kingdoms who feared her because of what she could have been capable of. 

As was the case with Jean Grey. As a child, she showed powers that shook even the likes of Charles Xavier. 

So much so, that he agreed to meet his arch nemesis Erik Lensherr and help him convince her to join them.

Both characters were unwillingly suppressed by people they thought to be their family and their mentor.

According to the original X-Men trilogy when Charles Xavier had found out about Jean’s other personality- The Phoenix, he had suppressed it inside her. 

Viserys had always kept Dany under control until his death. 

Both the characters willingly accepted death, only to come back stronger than any other creature in their universe. 

Daenerys, of course, went into the funeral pyre and came out as the unburnt mother of dragons. 

Jean had to sacrifice herself to save her fellow X-Men in X2: X-Men United but was saved by the Phoenix force suppressed inside her. 

BTW, both women also killed their bald advisors.

Varys tried to tell the entire realm that Jon was the true king of the Iron Throne. So Daenerys got Drogon to roast him alive. 

Jean disintegrated Charles Xavier in a fit of uncontrolled rage when she learnt that he was trying to control her. 

Both Dany and Jean, murdered thousands of innocent people, which eventually led to their downfall.

Led into battle by Magneto, Jean sees that the humans have been trying to trick them into losing their powers. On seeing this, she loses it and obliterates everything around her. 

Daenerys, as we all know, though a victim of poor writing, did burn an entire city to the ground for no apparent reason. 

As they had killed the first men they had loved, both the characters were literally killed in the same fashion, by the last men they had loved. 

Logan approaches Jean and tells her that he loves her before stabbing her through the heart. She dies in his arms. 

Jon Snow, on the other hand, despite not wanting it, tells her that she would always be his queen and then stabs her. 

Those are some uncanny similarities, aren’t they? That being said, these are purely circumstantial as I’ve mentioned above. So don’t take it to heart.