Here's a list of several men directly or indirectly considered "apostles" in the New Testament who were neither members of the Twelve nor authors of Scripture:
1. BarnabasExplicitly called an apostle with Paul in Acts 14:14.2. James, the Lord’s brotherCalled “James the Lord’s brother” and designated “an apostle” in Galatians 1:19 (Greek: Ἰάκωβος ὁ τοῦ κυρίου ἀδελφός καὶ ἀπόστολος).3. Silas (Silvanus)Described as an apostle in the Greek of 1 Thessalonians 1:1 and 2:6 (where he is called “Silvanus, a brother, and an apostle”). Sent by the Jerusalem church with Paul and others (Acts 15:22, 27, 32) and travels with Paul in Acts 15–18.4. TimothyAlso styled an apostle in the Greek of 1 Thessalonians 1:1 and 2:6 (with Paul and Silas). Missionary (apostolic) companion of Paul, but not one of the Twelve and not the author of any NT book.5. EpaphroditusCalled “your apostle and minister of my need” in Philippians 2:25 (Greek ἀπόστολον).6. ApollosGenerally treated as an apostle by some scholars, though the word apostolos does not appear in Apollos’ own name‑passages (Acts 18–19; 1 Cor. 3–4). If only explicit NT uses of the noun apostolos* are required, Apollos might be excluded; but where lists are drawn (e.g., explaining “the apostles” in 1 Cor. 1:12; 3:22; 4:9), he is often classed in the apostolic circle.7. Unnamed “apostles” in 2 Corinthians 8:232 Corinthians 8:23 speaks of “messengers** of the churches, the apostles **of Christ” (Greek ἀπόστολοιἀπόστολοι).8. TitusWhile not titled "apostle," the nature of Paul's instruction in Titus (as well as pertinent narrative portions in Acts) and of his co-working with Paul shed light on his role, which appears not only to be one of a "helper" or even an "elder," but fits much more within the apostolic ethos and function.
None of these apostles were members of the Twelve, recipients of original foundational revelation (like Paul), nor authors of Scripture. Suffice it to say, while it's clear that there can be no apostles added to the category of the Twelve, nor can there be new apostles who receive authoritative revelation that's binding for the Church in all ages (Scripture is sufficient), it's also clear (from Scripture itself!) that certain kinds of apostles lived and labored outside of those categories in the NT.
A few of them were more like messengers between the churches. But most of them were Gospel preaching, elder-qualified, elder-appointing, spiritually fathering, disciple-making church-planters. (Paul clearly fit in this category as well, though direct revelation of the Gospel and NT authorship were unique to his apostleship, of course. We could also add that NT authorship was not definitive of nor central to apostleship in the NT. Most of the Twelve, in fact, were not authors of NT books, much less the men listed above. Ordination to biblical authorship was simply a feature of some of the NT apostles rather than being definitive of it, broadly speaking.)
I am convinced that this role of apostleship should be seen as ongoing, and that the lack thereof has led to all kinds of improprieties and errors in the work of the Great Commission. It has led to well-meaning hastiness in the laying on of hands, and to sending men who may be noble and sincere in many respects, but aren't yet equipped for the task. It is a truncated thing to define "missions" exclusively as evangelism in a foreign field. The (non-12, non-bible writing) apostles did more than that in the NT.
Therefore, when I take up Matthew 9.37-38 in prayer for the advance of the Gospel in America and to the uttermost parts of the earth, I'm praying especially for these kinds of "laborers/workmen" (ἐργάτας)--- Men fit to lead teams of co-workers for the task spelled out in Scripture.
God has many such men at work among the nations, I'm convinced. They are largely unknown in the popular ministry spheres. But we haven't enough. "The laborers are few," indeed, and the Great Commission will require many more. These are the kinds of men we are laboring to shepherd and equip in our local church, and I think all churches ought to be doing the same.
Some are, and I thank God for them. Others are not. I think we're in need of a Reformation of sorts along these lines. May the Lord of the harvest raise up faithful men of this kind, for "the fields are white unto harvest," and the nations are in need of clear Gospel-preaching, real discipleship and spiritual fathering, and the establishing and nurturing of healthy local churches.
This is our aim until the blessed Lord appears. - BA Purtle