Pseudepigrapha are spurious works ostensibly written by a biblical figure. Deuterocanonical works are those that are accepted in one canon but not in all.
Old Testament Pseudepigrapha are extremely numerous and offer accounts of patriarchs and events, attributed to various biblical personages from Adam to Zechariah. Some of the most significant of these works are the Ascension of Isaiah, the Assumption of Moses, the Life of Adam and Eve, the First and Second Books of Enoch, the Book of Jubilees, the Letter of Aristeas, and the Testaments of the Twelve Patriarchs.
All the New Testament apocrypha are Pseudepigraphal, and most of them fall into the categories of acts, gospels, and epistles, though there are a number of apocalypses and some can be characterized as wisdom books. The apocryphal acts purport to relate the lives or careers of various biblical figures, including most of the apostles; the epistles, gospels, and others are ascribed to such figures. Some relate encounters and events in mystical language and describe arcane rituals. Most of these works arose from sects that had been or would be declared heretical, such as, importantly, the Gnostics. Some of them argued against various heresies, and a few appear to have been neutral efforts to popularize the life of some saint or other early leader of the church, including a number of women. In the early decades of Christianity no orthodoxy had been established, and various parties or factions were vying for ascendancy and regularity in the young church. All sought through their writings, as through their preaching and missions, to win believers. In this setting virtually all works advocating beliefs that later became heretical were destined to denunciation and destruction.