The Tennis-Playing Robot is a supporting character of Barbie: Life in the Dreamhouse. It was created by Ken during Happy Birthday Chelsea and presumably disassembled shortly afterwards, however Ken reassembled it following Chelsea's announcement that all she wanted for her sixth birthday was a Tennis-Playing Robot.
The Tennis-Playing Robot is accidentally created by Ken while trying to put together a bicycle for Chelsea's sixth birthday. Immediately after powering up, it begins to pelt Ken with tennis balls from the Little Miss Cupcake-elator attached to its right "arm". It is unknown if this was a deliberate malicious attack or whether it was just doing what it was programmed to do.
In Ken and Robot, it stares forlornly at the camera following Ken's joke, suggesting that it might not be as malevolent as its Ken-hating supporting characters Schlond Poofa and the Fish.
Like Closet, the Tennis-Playing Robot was created accidentally by Ken, thus making the doll its father and the omnipresent organisation system its brother.