From The TimeSplitters Wiki

Drone Splitter
Unlocked by	Elite League > Sincerest Form of Flattery > Half-Death with Silver or Better
Species	Alien
Size	Normal
Accuracy	7 of 10
Agility	3 of 10
Stamina	5 of 10
Fire Proof	N/A
Shock Proof	N/A
Default AI	4
Native TimeZone	2401
First Appearance	TS2 Story Mode
Relations	Baby Drone
Games	TS2

TS1 Gesture	N/A	TSFP Gesture	N/A
TS2 Gallery	Once a peaceful amphibian race, the Drones were enslaved when the Splitters invaded their planet. Spinal implants ensure they will never escape the Splitters control.	TSFP Gallery	N/A

The Drone Splitter despite their name and affiliation are not TimeSplitters. They are an alien race that was enslaved by the TimeSplitters. Cortez encounters them in the Space Station in TimeSplitters 2.