Short answers, pulled from the story.
Gaius Marius held the consulship seven times, an unprecedented number in Roman history. He was consul from 107 BC and then consecutively from 104 to 100 BC, and finally for a seventh time in 86 BC, dying within a fortnight of assuming that last office.
Gaius Marius was born around 157 BC in Cereatae, a small village near the town of Arpinum in south-east Latium. Arpinum had received full Roman citizenship only in 188 BC, thirty years before his birth.
Marius defeated the Teutones and Ambrones at Aquae Sextiae (modern Aix-en-Provence) in 102 BC, with estimates of between one hundred thousand and two hundred thousand killed or captured. The following year, in 101 BC, he and his colleague Quintus Lutatius Catulus destroyed the Cimbri at the Battle of Vercellae, where upwards of one hundred and twenty thousand Cimbri perished.
Sulla served as Marius's quaestor during the Jugurthine War and was instrumental in securing the capture of Jugurtha. Their rivalry began when both men disputed credit for that capture. It culminated in 88 BC when Marius attempted to seize Sulla's command against Mithridates, leading Sulla to march his army on Rome, defeat Marius, and issue a death sentence against him.
Nineteenth-century historians credited Marius with sweeping reforms, including shifting Rome to a professional soldiery and redesigning the pilum. Twenty-first-century specialists largely regard these so-called Marian reforms as a construct of modern scholarship. The recruitment of men without property in 107 BC appears to have been a one-time emergency measure, and armies of the late Republic were still predominantly raised by conscription from rural populations.
Marius died on the 13th of January, 86 BC, in Rome, within a fortnight of taking office as consul for the seventh time. Ancient sources disagree on the cause: Posidonius attributed his death to pleurisy, while another tradition describes him in a delirious final state imagining himself commanding the war against Mithridates.