NiGHTS from the NiGHTS series. This model is from NiGHTS into Dreams...
Original model by Sonic Team, reuploaded to the Source Engine for Garry's Mod by Mr. Nobody on Steam. The original author is unknown.

https://steamcommunity.com/sharedfiles/filedetails/?id=701657755
https://steamcommunity.com/profiles/76561198049094331

To install, navigate to your Tony Hawk's Underground 2 > Game > Data > models directory and choose either your Skater_Pro or Skater_Secret folder. Rename the files
for the model you want to use to match the Skater_whatever.skin.xbx and Skater_whatever.tex.xbx files and replace. This model is already set to replace Chad Muska 
in the Skater_Pro folder.

Also included are the dummy skaterparts files required for this and many other character model ports for Tony Hawk's Underground 2 / THUG Pro to work. If you don't
already have these installed, copy and paste all three .prx files to Tony Hawk's Undergound 2 > Game > Data > pre, and replace the original files with these ones.

IT'S HIGHLY ADVISED TO BACK UP YOUR MODELS FOLDER BEFORE REPLACING CHARACTER MODELS.