Lictors are a strain of Tyranid creatures bred with skill in infiltration. They are adept at assassination missions and are capable of lying dormant in dense foliage on a target planet for an incredibly long period of time.
Once the swarm initiates the attack against the target planet the Lictors will leap into action perverting the local wildlife and plants to the Tyranids causes. Lictors are equipped with a pair of large scything talons, deadly claws that can pierce even the heaviest of armour and a maw of feeder tendrils that can scan the brains of the Lictors unfortunate victims in order to find out information about the enemy defences or other pieces of strategic value to the Tyranid swarm.
In Dawn of War II the Lictor is a commander choice for the Tyranid army. In game the Lictor functions much like it does in both the tabletop game and the 'fluff' [fluff: background material, stories etc]. The Lictor can infiltrate making it invisible until it gets too close to an enemy, uses an ability or is revealed by a unit designed to reveal infiltrating units. Its attacks are powerful but the Lictor is also very fragile and will quickly perish under any kind of concentrated fire. This makes the Lictor much more effective at eliminating exposed and isolated targets rather that a suicidal charge into the foe.
The Lictor has an ability called 'flesh hooks'. This ability fires a number of fleshy spines into the enemy that deal damage and draw the enemy towards the Lictor.