Doctor Vassbinder was a professor at Starfleet Academy in the 24th century.
During his time as Starfleet Academy, Chakotay failed Professor Vassbinder's course in temporal mechanics. (VOY: "Year of Hell, Part II")
Vassbinder also lectured at the physiognomy workshop during a psychological conference on the effects on deep space assignments in 2369. He mistakenly gave an hour-long dissertation on the ionization effect of warp nacelles where the topic in question was supposed to be psychology. His presentation style both bored the attendees and prevented them from alerting him to his mistake; Captain Picard stated, "He just kept talking in one long incredibly unbroken sentence moving from topic to topic so that no-one had a chance to interrupt; it was really quite hypnotic." (TNG: "Timescape")
In 2370, Vassbinder published some new theories on warp propulsion inter-relays, which Wesley Crusher used to discredit Geordi La Forge's work on a new plasmadyne relay for the USS Enterprise-D's warp core. (TNG: "Journey's End")
This character was only mentioned in dialogue.
Vassbinder was named after a high-school teacher of Brannon Braga's. (Star Trek: The Next Generation Companion, 2nd ed., p. 251)
According to the Star Trek Adventures - The Sciences Division sourcebook, his full name is Ernst Vassbinder.