Most people will see Fiona Shaw and think Aunt Petunia from the Harry Potter series. I, on the other hand, immediately flash back to her character "Lena" from the Super Mario Bros. movie...

The third season of True Blood saw the addition of at least a half dozen new cast regulars and season 4 appears to be doing the same. The fourth season will be focusing on witches and witch craft with Shaw's character playing  a medium and palm reader named "Marnie".  Deadline reports that the character is "... a mousy, timid and secretly self loathing storefront medium and palm reader who is taken over by the spirit of a powerful witch."

Source: Deadline