Since GMod 10 is an older version, you need to look for legacy-compatible files.

Download Nextbots or monsters from games like Resident Evil.

Primarily for the latest version, but many "Legacy" tags work with older builds. Popular NPC Types to Download

the game and look for your new friends (or enemies) in the "NPC" tab of the Spawn Menu.

These have custom AI and don't just stand there; they hunt you down.

I can find direct download links or troubleshooting steps for your .

Give the Combine or Rebels a fresh look with new tactical gear.