Do all robot vacuums have a brush roll?

No, not every robot vacuum has a brush roll. Brush rolls flick dirt loose from carpets, so if you have carpets, check before you buy. Models that include one are the [iRobot Roomba](https://www.amazon.com/s?k=iRobot+Roomba&tag=wehavethat-20) 694, [Roborock S](https://www.amazon.com/s?k=Roborock+S&tag=wehavethat-20)7 MaxV Ultra, Eufy RoboVac X8 Hybrid, [Shark AI](https://www.amazon.com/s?k=Shark+AI&tag=wehavethat-20) Self-Empty XL, and Dreame Bot. A brushless vac on carpet is basically a dust shuffler.