The Correspondence of (or between) Paul and Seneca, also known as the Letters of Paul and Seneca or Epistle to Seneca the Younger, is a collection of letters claiming to be between Paul the Apostle and Seneca the Younger. There are 8 epistles from Seneca, and 6 replies from Paul. They were purportedly authored from 58–64 CE during the reign of Roman Emperor Nero, but appear to have actually been written in the middle of the fourth century (c. 320–380 CE). Until the Renaissance, the epistles were seen as genuine, but scholars began to critically examine them in the 15th century, and today they are held to be inauthentic forgeries.

Paul of Tarsus was an early Christian theologian and evangelist, who wrote epistles to Christian communities and founded multiple churches across the Greek-speaking Eastern Mediterranean region. Seneca the Younger was one of the foremost philosophers of Stoicism, a teacher and adviser to Emperor Nero, a dramatist, and a Roman government official. The correspondence between them comprises fourteen letters in total (8 from Seneca, 6 from Paul) and is written in Latin. It has little substantive content. It largely consists of the two praising each other; Seneca lavishes flattery on Paul, while Paul responds in kind. For example, the first epistle from Seneca states that "[Paul's works] are so lofty and so brilliant with noble sentiments that in my opinion generations of men could hardly be enough to become established and perfected in them. I wish you good health, brother." Essentially, the main interest of these letters is that they exist at all: they ostensibly demonstrate that Paul was important and respected enough to trade letters with the eminent philosopher Seneca, that Seneca was wise enough to understand Paul's greatness despite being a pagan, and that the two were friends.

Many, but not all, surviving manuscripts include dates on some of the letters of the correspondence. The earliest of these is "27 June in the consulship of Nero III and Messala" (58 CE) and the latest is "28 March in the consulship of Frugi and Bassus" (64 CE). The one epistle that does include substantive content is the 11th one dated 64 CE, which directly discusses the Great Fire of Rome.

The earliest known reference to them is in Jerome's On Illustrious Men chapter 12, a work of around 392 CE:

Lucius Annaeus Seneca of Cordova, a disciple of the Stoic Sotion, and paternal uncle of the poet Lucan, was a man of very temperate life whom I would not place in a catalogue of saints, were it not that I was prompted to do so by those Letters from Paul to Seneca and from Seneca to Paul which are very widely read. In these, when Seneca was Nero's teacher and the most influential person of the period, he said that he wished to have the same position among his own [i.e., the pagans] which Paul had among the Christians. Two years before Peter and Paul were crowned with martyrdom, he was put to death by Nero.

— Jerome, De Viris Illustribus (On Illustrious Men)

Augustine of Hippo also briefly mentions the correspondence, as does Pseudo-Linus. During the late fourth and fifth century, such a correspondence was both plausible and interesting to educated Roman Christians. The Acts of the Apostles claims that Paul briefly met Seneca's brother, Gallio. Paul's Epistle to Philemon says he was imprisoned in Rome and that the Praetorian Guard knew of this; the Guard was at one point commanded by Burrus, an ally of Seneca. Stoicism, much like Hellenistic Judaism, was considered a precursor to Christianity that helped influence its stances and terminology; conscientia ('conscience') was originally a Stoic term, for example, and Stoicism's criticisms of the (pagan) Roman religion was something Christians were eager to take for themselves as well. The Christian polemicist Tertullian called Seneca "saepe noster" ("often ours") and approved of his criticism of pagan superstition. The correspondence was in circulation during the Middle Ages among Latin-reading areas (Western Europe, rather than the Greek-reading Byzantine East), and likely contributed to Seneca having a good reputation among medieval Christians. The medieval authors Peter of Cluny, Peter Abelard, and Petrarch all seem familiar with the correspondence. A few medieval writers such as Giovanni Colonna and Giovanni Boccaccio even claimed that Seneca had outright converted to Christianity before his suicide in 65 CE, partially on the basis of the correspondence.

Scholars almost universally believe the correspondence to be forged. During the 15th century in the Renaissance, more skeptical analysis raised doubts on the veracity of the correspondence. Scholars such as Lorenzo Valla found that the writing style matched neither Seneca nor Paul, and the letters were denounced by Erasmus. Later scholars detected errors of fact and chronology that the genuine Seneca would not have made, but a forger not intricately familiar with Roman history writing centuries later might have. Scholars noticed with skepticism just how late the letters appeared in history; Lactantius, a Christian author writing earlier in the 4th century, makes no mention of any such correspondence, despite frequently citing Seneca and positively evaluating both him and Paul. This suggests their creation in the middle of the 4th century, such that Lactantius would have been unfamiliar, yet Jerome would think them legitimate. The Latin style of the collection is also a good match to 4th-century works, such as the letters of Symmachus.