High Quality Content by WIKIPEDIA articles! Gaius Sempronius Gracchus (154 BC – 121 BC) was a Roman Populari politician in the 2nd century BC and brother of the ill-fated reformer Tiberius Sempronius Gracchus. His election to the office of tribune in the years 123 and 122 BC and reformative policies whilst in office prompted a constitutional crisis and his death at the hands of the Roman Senate in 121.