What Came First: The Character or the Plot?

What comes first when you write, character or plot?

With pretty much everything that I have written, it was the plot that came to me first. Specific characters formed and gave the story life later down the line, only once I had let the idea stew for a while and started plotting. Recently however the image of a character appeared in my mind so vividly; it was truly bizarre, like nothing I had ever experienced before.

I don’t yet know exactly what story will end up forming around this character (and what’s interesting is that I think she will likely take on a supporting role rather than that of the protagonist) but I already see (as cheesy as it may sound) so much of her, from her Asian heritage to her confident mannerisms; from her dry humour to her fierce intelligence; from her name to her career; this is a character I just have to do something with in the future, however far off it may be.

Do you usually come up with characters or plots first? Have you ever been struck by a character or plot idea unexpectedly?