So my group are a bunch of hopelessley foul WH nerds who read a fair bit of Black Library books. Therefore, I was thinking of having characters of Black Library fame appear in my campaigns. Potential candidates are Gotrek Gurnisson and Felix Jaeger, Detlef Sierck the Playwright, and Luthor Huss. I don't want them to play huge roles in the adventures, just being there to spice things up and letting the players see a 'familiar face'.

Do you have any experience doing this? Is this a bad idea?

I think it's fine and vibrates with the Warhammer fluff to have "big name" folks appear or be mentioned and eventually even met.

They just shouldn't, as in any RPG, take the story focus and pressume off PC's - who are the stars of their own story.

In my own campaign (Crusade of the Child), I have featured mentions of Luther Huss for example in talking about corruption within the Cult of Sigmar that blends then with why followers of the Child Karl often hope for a house-cleaning of the cult as part of their vision of Karl's destiny, he was in Marienburg preaching before Karl was revealed and that stirred up Sigmarites there - in a way paving the way for Karl (Karl has some fluff similarities to Valten - who is not part of my campaign/timeline at this point). Depending on how things go, he may figure even more prominently but not as "a deus ex machina, just bring the problem to Huss and it's solved" thing. I have used a throwaway line about play by Detlef in passing but not worked him in any more than that.

I think you're absolutely right. The players are the stars of the show.

I'm currenly thinking of having Deltlef Sierck write and star in a play about the player's adventures (TEW++), as a sign of recognition, similar to the novel Drachenfels. Totally distorted and hyperbolic, of course.

That could be fun, the play. Taking a spin off Drachenfels, he's getting his info from an enemy of theirs distorting things or even trying to draw them to attend to be assassinated etc., he's excited by the inspiration, some of his best work and doesn't want to change the play, etc. Spinning even furthre, the "altered version" in the play is part of a ritual to undo something they did……

Thanks for the suggestions, I'll keep things updated in this thread.