Update: More discussion on the forum.
Tired of Orcs and Goblins? The Grendel is a new humanoid opponent that will provide some challenges for PCs, including higher hit dice and a few special skills.
AC 5 
ATK Bite 1d3x2 or weapon 1d6 (see below)
SP Surprise on 1-3/1d6
Grendel are fearsome, disfigured humanoids with large ears, mottled skin, and sharp, extruding teeth. They are highly skilled at sword fighting and typically attack with two blades, gaining +1 to-hit and the better of two damage rolls if they do hit. They will also carry a few throwing knives secreted about their person, which can be used as missile weapons at short range (within 20 feet) for 1d6 damage with +1 to-hit. Grendel can bite twice per round for 1d3 damage if they are disarmed.
Thankfully, they disdain traveling in large groups, preferring smaller groups of perhaps five to six with lone scouts sent ahead. Such scouts are quite stealthy when encountered alone, surprising on a 1-3/1d6. They move quickly and prefer to travel lightly. Female Grendel are just as fearsome as their male counterparts, and can be found in equal numbers amongst patrols. They like to live in small communities in shallow caves or outdoors in shelters of their own making. Such encampments will be protected by various snares and traps around their perimeters.
Grendel tend to be distrustful of even their own race, and will hide treasure in secretive places. They like to train and use wolves as guard animals.
Monster stats key:
- AC – Armor class – given in both descending and [ascending] format.
- HD – Hit dice. D6 for Whitebox, D8 for other editions.
- ATK – Attacks and damage.
- SP – Special abilities or notes.
- MV – Base Move rate.
- HDE/XP – Hit Dice Equivalent/Experience points
- SAV – Saving throw. This is a single save as normal per Swords & Wizardry rules.
- BHB – Base hit bonus. Used with Ascending AC combat, the DM rolls a d20 and adds the BHB. If it is higher than the opponent’s AC, it is a hit. Handy as no chart is needed.
- AL – Alignment (lawful, neutral, or chaotic)