A class 8 probe was a type of probe used by the Federation in the late 24th century, usually instrumented heavily with sensor and transceiver equipment, and was designed for extended flight at velocities up to warp 9. Class-8 probes were based on the photon torpedo spaceframe.
Though not specifically designed to transport a person, it was a class 8 probe in which special emissary K'Ehleyr left Starbase 153 and arrived on board the USS Enterprise-D on stardate 42901.3. On this stardate, the sensor equipment was replaced by a life support system, capable of sustaining one person. She described it as a coffin and a Class-A probe. (TNG: "The Emissary")