Appius Claudius Sabinus Regillensis or Inregillensis (fl. 505 – 480 BC) was the legendary founder of the Roman gens Claudia, and consul in 495 BC. He was the leading figure of the aristocratic party in the early Roman Republic.

Appius Claudius was a wealthy Sabine from a town known as "Regillum". His original name was Attus Clausus or Attius Clausus, according to Livy; Suetonius gives Atta Claudius, while Dionysius of Halicarnassus gives Titus Claudius. From the Fasti consulares, it is known that Claudius' father was named Marcus. He had at least two sons: Appius Claudius Sabinus Regillensis, consul in 471 BC, and Gaius Claudius Sabinus Regillensis, consul in 460 BC. Appius Claudius Crassus, the decemvir, was his grandson.

In 505 BC, shortly after the establishment of the Roman Republic, Rome successfully waged war against the Sabines, and in the following year, the Sabines were divided as to whether to retaliate or make peace with the Romans. Clausus favoured peace with the Romans, and as the faction favouring war became more powerful, he migrated to Rome with a large group of his clients, and took the name Appius Claudius. In recognition of his wealth and influence, he was admitted to the patriciate, and given a seat in the Senate, where he quickly became one of the leading men. His followers were allotted land on the far side of the Anio, and along with other Sabines formed the basis of the "Old Claudian" tribe.

In 495 BC, nine years after he arrived at Rome, Claudius was consul with Publius Servilius Priscus Structus. He may previously have been quaestor. The consulship of Claudius and Servilius was marked by the welcome news of the death of Tarquin at Cumae, where the last King of Rome had fled after the Battle of Lake Regillus. However, the end of a threat which had unified the social strata at Rome also encouraged the patrician aristocracy to take advantage of its position, foreshadowing the approaching Conflict of the Orders. New settlers were sent to Signia, where a colony had been established by the old king; the tribus Claudia was formally incorporated into the Roman state; and a new Temple of Mercury was completed.

Meanwhile, the Volsci began preparations for war, enlisting the aid of the Hernici and approaching the Latins. Stung by their recent defeat at Lake Regillus, the Latins were in no mood for war, and instead delivered the Volscian envoys to Rome, warning the Senate of the pending military threat. In gratitude, six thousand Latin prisoners were released, and the Senate agreed to consider a treaty with the Latins, which had previously been refused.

But the city's attention was suddenly diverted from the threat of war with the Volsci by the appearance of chained men, who had been handed over to their creditors after falling irretrievably into debt, among whom was an old soldier who had lost his home and property while fighting for his country in the Sabine war. Cries for justice soon overtook the streets, and the consuls hastily attempted to convene the Senate, although many of the senators hid in fear for their lives. Claudius urged the arrest of the supposed troublemakers, supposing that the people would be cowed if an example were made of their leaders. Servilius, meanwhile, urged the Senate to negotiate with the plebeians in hopes of resolving the crisis.

While the Senate was debating, news arrived from Latium that the Volscians were on the march. Popular sentiment was that the patricians should fight their own war, without aid from the plebs; so the Senate, feeling that the consul Servilius would be more likely to gain the trust of the plebeians in this time of emergency, entreated him to effect a reconciliation. Servilius addressed the people, urging them that they need unite against a common threat, and that nothing could be gained by attempting to force the Senate's action. He declared that no man who volunteered to serve against the Volscian invasion might be imprisoned or given over to his creditors, nor should any creditor molest the families or property of any soldier, and that those who had already been shackled should be freed in order to serve in the coming battle.

After detecting a Volscian surprise attack, the consul Servilius, in whose vanguard were many of the freed debtors, led a successful assault on the Volsci, who broke and fled. Servilius captured the Volscian camp, and continued on to the Volscian town of Suessa Pometia, which he also took. A Sabine raiding party took advantage of the consul's absence to enter Roman territory, but they were pursued by Aulus Postumius Albus Regillensis, the former dictator, until Servilius was able to join him, and the two routed the Sabines. No sooner had they done so, than envoys arrived from the Aurunci, threatening war unless the Romans departed the territory of the Volscians. While Rome prepared her defenses, Servilius marched against the Aurunci, and defeated them decisively in a battle near Aricia.