TARS and CASE are the two robots which are part of the Endurance crew.
The Interstellar wiki explains
TARS is a former marine robot with angular limbs and a sarcastic attitude.
CASE is one of three former marine surplus robots, alongside TARS and KIPP, CASE first appeared within an alcove onboard the Endurance mission.
Is there a significance to the names of the robots, or why were they named as such? Are they unique serial numbers (similar to R2-D2 and C-3PO)? The fact that the names are written in all caps on their bodies lends weight to the idea that they may be acronyms.
I'm hoping for an in-universe answer if possible. It wouldn't make much sense for the military to name them after people who assisted in the creation of the film.