From an interview with Kristian Nairn (GoT)

...Because of the show's expansive cast and various, far-flung filming locations, there has never been an occasion when every actor on the series has been in the same room. So it was several seasons before Nairn had an opportunity to meet Charles Dance, who plays Tywin Lannister on the series and is the co-star Nairn says he admires most as an actor. But the first time he met Dance, Lairn abandoned his co-star mid-conversation because one of his idols, Sally Field, happened to walk by.

If you want to know if Field has the power to transform a 6'10" Irish actor into a sputtering, fawning fan girl, the answer is yes. Lairn lost all ability to have a normal conversation in the presence of Field, and he says the sight of him towering over while asking her if she was enjoying her night probably terrorized her.

Lairn meant to apologize to Dance for his inadvertent rudeness, but the two have not had the occasion to meet since;

http://www.sacurrent.com/Blogs/archives/2015/09/12/hodor-hates-john-snow-and-hopes-he-stays-dead