Neil Patrick Harris and Orlando Bloom
Oddly enough, NPH and Orlando Bloom mashed together literally just looks like NPH. Oddly enough, they really do look similar! It looks like the artist used Patrick-Harris' mouth, eyes, and nose but used Bloom's facial features for the rest. Still, the difference is barely there.
Emilia Clarke and Kit Harington
Emilia Clarke played the Mother of Dragons herself in Game of Thrones. Kit Harington played the Stark son who ended up becoming King of the North for a quick bit. Naturally, the two developed a relationship. If things had actually gone well in the end, maybe their daughter would have ended up looking like the human on the right.