Do the sigils next to the names of staff in the Game of Thrones intro all exist in the fictional world?

Question

We know that the animation of the Game of Thrones intro represent the locations in which the story of the current episode resides.

During the intro, we see the names of the actors and the names of some of the behind-the-scenes staff of Game of thrones. All names are displayed together with a sigil. The sigils of the actors are the sigils of the houses their character belongs to. Sophie Turner for example has the sigil of house Stark next to her name: A Direwolf.

The credits of behind the scenes crew also have a sigil next to their name. Some of these sigils are used multiple times, Ramin Djawadi (music) and George R. R. Martin (author) share the same one. What I am wondering is: Do these sigils actually exist in the world of Game of Thrones and if yes: which houses do they belong to?

It would also be interesting to know how it was decided whom is going to have which sigil next to their name.

Answer 1

They are more of personal choice or sometimes jokes:

For George R.R. Martin

Martin has chosen a turtle as his personal sigil, and he is often seen wearing a hat with a turtle pin on it. As Martin himself explained at the Game of Thrones panel for San Diego Comic Con 2012:

"Turtles have always been my sigil, I suppose. When I was a kid, growing up in Bayonne, NJ, I lived in a federal housing project, and we were not allowed to have a dog or cats. The only pets I could have were turtles. So, I had an entire toy castle filled with dime-store turtles. I gave them all names, and since they were living in a toy castle, I decided they were all knights and kings...and I made up stories about how they killed each other and betrayed each other and fought for the kingdom. So, Game of Thrones, actually began with turtles. I decided later to recast it with actual human beings."

For Bryan Cogman

The sigil next to Cogman's name in the opening credits is actually a vomiting maester - a joke by Benioff and Weiss, referencing how at the Season 1 wrap party, Cogman had too much to drink and had to throw up

He even mentioned it himself in a tweet (now deleted):

Most of us producers got to choose our personal sigils for the opening credits. Except me. D&D personally commissioned the vomiting maester

— Bryan Cogman (@b_cogman) April 8, 2016

Ramin Djawadi, Gemma Jackson, Guymon Casady and Deborah Riley have turtle as their sigil too.

Carolyn Strauss has an Ostrich

The symbol of Ostrich has a famous relation with the surname Strauss:

The name has been used by families in the Germanic area for at least a thousand years. The overlord of Gröna, for example, went by the name of Struz and used the image of an ostrich as his symbol. Examples of it could still be seen on the thousand-year-old church bell of that town. "Struz" or "Strutz" is the North-German form of the word "Strauss", which is the modern German word for ostrich.

Took images and some inspiration from the answer on a similar question from our sister sci-fi site, which also provides additional sigils for rest of the crew too:

Where are the cast and crew logos in Game of Thrones opening credits from?