Genlocks are the most numerous breed of darkspawn. They are short, stocky, and easily killed. They can, however, pose a challenge in large numbers.
How Genlocks appear in Dragon Age: Origins
Background
These are the basic infantry of the darkspawn horde. Genlocks often accompany Hurlocks in battle as archers.
Skills
Origin
Genlocks are born from broodmothers that were once female dwarves. Since the dwarves regularly fight darkspawn, this would explain why genlocks are the most common type of darkspawn.