Question: During the Hunnic Invastion of 451 Flavius Aetius ended the invastion of a ruler who was the leader of the Huns, Alans and what other groups of people?
Context: Aignan, or Agnan ("Latin": Anianus) (b. 358–d. 453), Bishop of Orléans, France, assisted Roman general Flavius Aetius in the defense of the city against Attila the Hun in 451.  He was canonized and is known as Saint Aignan.  His remains are buried in the Church of Saint Aignan in Orléans. Gondioc (Proto-Germanic: "*Gunþawīgaz" ; died 473), also called "Gundioc" and "Gundowech", was King of the Burgundians following the destruction of Worms by the Huns in 436, succeeding Gundahar.  In 451, Gondioc joined forces with Flavius Aetius against Attila, the king of the Huns, on the Catalaunian Plains.  Gondioc married the sister of Ricimer, the Gothic general at the time ruling the Western Roman Empire. The Huns were a nomadic people who lived in Eastern Europe, the Caucasus, and Central Asia between the 4th century AD and the 6th century AD.  According to European tradition, they were first reported living east of the Volga River, in an area that was part of Scythia at the time; the Huns' arrival is associated with the migration westward of a Scythian people, the Alans.  By 370 AD, the Huns had arrived on the Volga, and by 430 the Huns had established a vast, if short-lived, dominion in Europe. Attila ( or ; fl.  circa 406–453), frequently referred to as Attila the Hun, was the ruler of the Huns from 434 until his death in March 453.  He was also the leader of a tribal empire consisting of Huns, Ostrogoths, and Alans among others, on the territory of Central and Eastern Europe. Sangiban was a fifth-century Alan king at the time of Attila's invasion of Gaul (451).  He was the successor of Goar as king of the Alan "foederati" settled in the region around Aurelianum (modern-day Orléans).  According to Jordanes, Sangiban had promised Attila before the Battle of Châlons to open the city gates and deliver Aurelianum to the Huns.  Suspecting this, the Romans and Visigoths put Sangiban in the center of the line opposing the Huns, where they could prevent him from defecting.  Thus the Alans bore the main brunt of the Hunnic assault, while the Goths were able to flank the Huns and ultimately drive them back. Flavius Aetius (Latin: "Flavius Aetius" ; 391–454), "dux et patricius", commonly called simply Aetius or Aëtius, was a Roman general of the closing period of the Western Roman Empire.  He was an able military commander and the most influential man in the Western Roman Empire for two decades (433-454).  He managed policy in regard to the attacks of barbarian federates settled throughout the Western Roman Empire.  Notably, he mustered a large Roman and allied ("foederati") army to stop the Huns in the Battle of the Catalaunian Plains, ending the devastating Hunnic invasion of Attila in 451. The Battle of the Catalaunian Plains (or Fields), also called the Battle of the Campus Mauriacus, Battle of Châlons or the Battle of Maurica, took place on June 20, 451 AD, between a coalition led by the Roman general Flavius Aetius and the Visigothic king Theodoric I against the Huns and their vassals commanded by their king Attila.  It was one of the last major military operations of the Western Roman Empire, although Germanic foederati composed the majority of the coalition army.  Whether the battle was strategically conclusive is disputed: The Romans stopped the Huns' attempt to establish vassals in Roman Gaul, and installed Merovech as king of the Franks.  However, the Huns successfully looted and pillaged much of Gaul and crippled the military capacity of the Romans and Visigoths.  The Hunnic Empire was later dismantled by a coalition of their Germanic vassals at the Battle of Nedao in 454. Flavius Gaudentius (or simply Gaudentius) (died 425 AD) was the father of the Roman "magister militum" Flavius Aetius and married to an Italian noblewoman.  He was of Scythian origin.  As the term "Scythian" was frequently used in the late-Roman period for East Germanic tribes, Joseph Cummins notes that Gaudentius was possibly of Gothic origin. "Comes" Bonifatius (anglicized as Count Boniface) (d. 432) was a Roman general and governor of the Diocese of Africa.  He campaigned against the Visigoths in Roman Gaul and the Vandals in Roman North Africa.  An ally of Galla Placidia (regent of Valentinian III), Bonifacius engaged in Roman civil wars on her behalf against the generals Flavius Felix in 427-429 and Flavius Aetius in 432.  Although he defeated the latter at the Battle of Rimini, Bonifacius suffered a fatal wound and was succeeded by his son-in-law Sebastianus as "patricius" of the Western Roman Empire. Flavius Felix (died 430) was a general of the Western Roman Empire, who reached the prominent rank of patrician before being killed by order of Flavius Aetius.  For his consulate, in 428, he issued some consular diptychs, one of which has been preserved until modern times.
Answer: Ostrogoths