Helena Bonham Carter is the first person to be confirmed outside of the Harry Potter trio to be back for Harry Potter and the Half-Blood Prince, the sixth film adaptation of the Harry Potter stories.
Bonham Carter will reprise the role of Bellatrix Lestrange after the character debuted in Harry Potter and the Order of the Phoenix. Filming on the sixth film is scheduled to begin in two months as Half-Blood Prince makes its journey toward its November 21, 2008 release date.
The sixth book is easily the least interesting of the series as not a lot happens. I truly expect it to be the shortest of the bunch as we lead up to Deathly Hallows, which should be one hell of a ride.