Hormagaunt
Hormagaunts are the Tyranids' basic assault organism. Equipped with a pair of Scything Talons, their job is to rush into close combat and slice things into nice small pieces. They can be assisted in this by the addition of Toxin Sacs or Adrenal Glands, making them even more killy. As they're members of the gaunt genus, they're unsurprisingly must effective when fielded in numbers, though they don't need quite the same numbers termagaunts do. Good for drowning your enemies in poisoned attacks.