Haruspex
The Haruspex is essentially the very embodiment of "OMNOMNOMNOM" (toppling the Rippers and rivalling the Mawloc) within the Tyranid race, which is saying something given the reputation of the 'Nids. Its specialty is in assault and eating things. Lots of things. To aid it in this task it has a mouth that wouldn't be too out of place in your average tentacle hentai. The tentacles work just as good for tearing apart enemy combatants as they do for eating said enemy combatants.
While the current design of the Haruspex is new the creature itself was in Epic where it looked like a slug with pincers and a pair of grabby claws on its back. Luckily it received a makeover to look more menacing, just like some other monstrous creatures.
It received an official model in a shared kit with the Exocrine in the 6th edition release of Codex: Tyranids.
In the grand GeeDubs tradition of Tyranid vocabulary names, "Haruspex" was the job title of a Roman fortune-teller. Except it was a specific brand of fortune telling what used sheep livers/intestines instead of anything reasonable and not-disgusting. Just in case you were wondering why the Haruspex looks like it's barfing up its own digestive system (which could also be an offensive version of stomach eversion, something that sharks in real-life do).
On the Tabletop
Another melee monstrous creature, though focused on infantry instead of vehicles. It can shoot out its tongue to grab things before charging, and it even has the Precision Shots rule on this tongue.
The general consensus is that it's situational and rather unimpressive, much like the rest of the Elites slots following the removal of Ymgarl Genestealers, the nerfing of the Hive Guards and Zoanthropes, the moving of the Deathleaper, and the lack of fixes to any of the problems that made Lictors and Pyrovores bad. Though at least the Venomthropes got better. However, it's presence does now mean the Tyranids have monstrous creatures in every slot. So with the exception of Termagaunts to unlock Tervigons it is now possible to make an all-Nidzilla list.
The Haruspex also appeared in Chapter Approved 2002, where it was given stats alongside some other creatures that at the time were not in the Codex. Costing only 105 points it was a lot better at fighting (superior WS, BS, I and LD), but it was less tough (W3 and 4+ save). This was offset by its rule, Fast, making it as fast as a Ravener which greatly helped getting in close. But even for a creature with so many claws it did not have rules for them in this iteration: rather it had a pair of ranged weapons: a S3 AP3 flame template and a 12" S5 AP4 Assault 3 Spinefist, meaning it excels at short-ranged shooting against medium infantry.