The Dark Heresy creature book, Creatures Anathema, has Genestealers and Lictors (and Ambulls, which warms my old skool heart!). The Deathwatch creature book Mark of the Xenos also has genestealers, brood lords, and a whole bunch of different Tyranids (though the basic stats for the more common Tyranid types are in the back of the Deathwatch core rules).
Oddly enough the stats for the two genestealers in the books mentioned above are very different. I think the idea is that they are different strains. The one in Mark of the Xenos would be quite a bit more of a challenge than its counterpart in the other book, as it is for the Space Marine game, which has much, much more powerful player characters than the mere minions of an inquisitor you find in Dark Heresy.