Ottó Titusz Bláthy (11 August 1860 – 26 September 1939) was a Hungarian electrical engineer. During his career he became the co-inventor of the modern electric transformer, the voltage regulator, the AC watt-hour meter, the turbo generator, the high-efficiency turbo generator and the motor capacitor for the single-phase (AC) electric motor.
Bláthy's career as an inventor began during his time at the Ganz Works in 1883. There, he conducted experiments for creating a transformer. The name "transformer" was created by Bláthy. In 1885 the ZBD model alternating-current transformer was invented by three Hungarian engineers: Ottó Bláthy, Miksa Déri and Károly Zipernowsky. (ZBD comes from the initials of their names). In the autumn of 1889 he patented the AC watt-meter.