The Skull Watch was a small group of mercenaries who have a grudge against the Republic.
The Skull Watch stole. Clone Armour during raids on Clone Training Centers at the beginning of the Clone Wars.
Created: 20 BBY
Leader: Skul Leton(AKA The Skull)
Main Members: The Skull
Main Raids: Kashyyk
Disbanded: 15 BBY(After Skul Leton was killed by a malfuntioning Training Droid that blasted his head off with a pulse canon)
Quoting Aaron Fett
There is one problem with this. If they began in 18 BBY its impossible that they could have raided Republic Outposts because Order 66 was issued in 19 BBY. Just thought I'd tell you.