In order, R-108, R-109 and R-110. As the series progresses, the robots get bigger and supposedly more advanced (although R-110's personality could suggest some other form of AI).
A robot from the R-100 Series has made an appearance in every TimeSplitters thus far. They are advanced robots created for The Machine Wars. The robots are often bulky and powerful, as they are designed to fight in war. A list of the R-100 robots is below.

• R-108
• R-109
• R-110