Eh, Slender Man may kill a few aliens, but the min he battled the first alien, it released a pharamon which allerted the whole hive, drawing the rest of the hive towards the scene, and depending on how dangerous the first alien judged The Slender man to be, the pharamon may have been strong enough to draw out The Queen, her royal guard, and any special alien the hive had in reserve, so in the end Slender man would have been probably pinned by their numbers, then had a face hugger attached. Boom A Slender Alien, completely loyal to the Hive.