Historic Editions of the Greek New Testament online

The Critical Editions of the New Testament Online
The Greek Text, Versions, and Transcriptions of Manuscripts
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This series, earlier published in a microfiche collection by IDC Publishers, makes available for the first time in a single online collection the principal critical editions, lists of variant readings and collections of manuscript transcriptions and collations from the late seventeenth to the early twentieth century. In addition, a number of the most useful editions of the ancient versions and of ancillary materials have been included. It begins with the first large collection, compiled by John Mill and published in 1707, and ends with von Soden’s huge work of 1902-13.

The most surprising thing was the price:

As Brill notes, this was previously published (before Brill’s acquisition of IDC Publishers) in a microfiche collection - contained in 853 fiche (Brill uses the same brochure):
But most of them are available for free somewhere on the internet, so I thought it would be helpful to see how many links we could collect here (with help from commenters): (I’ll start with abbreviated titles):

Greek New Testament

Erasmus (1516) (on later editions see Krans): Basel (e-rara): images & pdf; cspmt (pdf); images CSNTM

Complutensian Polyglot (vol five = NT) (1520?): cspmt (pdf)

Aldine (1518): cspmt (pdf)

Colines (1534): cspmt (pdf)

Stephanus (1550): cspmt (pdf); images CSNTM; Bibles online (nice images but fiddly orientation)
Beza (1588): good individual images at CSNTM
Beza (1598): cspmt (pdf)

Elzevir (1624): cspmt (pdf)

Elzevir (1633): cspmt (pdf)

Mill (1707) good individual images at CSNTM
Mill (rev. by Kuster) (1710) [Google Books] [HT Jan Krans] (BSB images & pdf)
Mill (2nd ed. Kuster) (1723) Google Books (BSB images & pdf)

J. A. Bengel (1734) at archive.org (google books) (NB. 1763 Apparatus criticus also at archive.org)

J.J. Wettstein, Prolegomena In Novum Testamentum: Cum Quibusdam Characterum Graecorum Et Latinorum In Libris Manuscriptis Exemplis (1730) [pdf at archive.org] (1764 rev by Semler at Google Books [images & pdf @ mdz])

J.J. Wettstein (1751-2), vol one (1751) at Marburg: images & pdf; vol two (1752) at Marburg: images & pdf [HT Jan Krans]; vol one at archive.org; vols 1(?) & 2 at Stanford/Google Books; hathitrust

Griesbach NT vol 1 (=Synopsis) (1776) [Google Books]
Griesbach NT vol 2 (1775) [GB]
Greisbach NT (1777): vol 1 (= Gospels & Acts) [Google Books]
Griesbach, Symbolae Criticae (1793) [Google Books]
Griesbach (1796), vol. 1, second edition (Google Books) (1806), vol. 2, second edition (Google Books) (BSB images & pdf)
Griesbach, Synopsis (1797, 2nd ed.) [Google Books]
Griesbach, Commentarius Criticus (1798) [Google Books]
(Griesbach NT vol 1, 1809 at archive.org; vol. 2, 1809)
(Griesbach NT vol 1, 1818 and vol 2, 1818)
Griesbach (1827, rev. Schulz) vol. 1 [Google Books]

Harwood, The New Testament (1776) [GB]
Matthaei (1782-1788) vol. 11: Matthew (1788); vol. 12: Mark (1788); vol 10: John (1786); vol. 1: Acts (1782); vol 5: Catholic Epistles (1782); vol. 3: 1&2 Corinthians (1783); vol. 6: Gal, Eph & Phil (1784); vol. 4: Hebrews & Col (1784); vol. 7: 1&2 Thess and Timothy);  vol.8: Apocalypse (1785).
Matthaei, Novum Testamentum Graece (vol. 1, 1803 [Google Books]; vol. 2, 1804 & vol. 3, 1087 [Google Books]) 

Alter (1786) [GB] [HT Jan Krans]

Lachmann (1831) [archive.org/Google Books]
Lachmann-Buttmann (vol. 1, 1842 [Google Books]; vol. 2, 1850 [Google Books]) (hathitrust)
Tregelles (1857) good individual images at CSNTM    Tyndale House
Tischendorf (NTG, vol. 1, 1869 [Google Books]; vol. 2, 1872 [Google Books]; Prolegomena (C.R. Gregory, 1890) [Google Books])
Westcott & Hort (1881)
von Soden (1902-13) good individual images of four volumes at CSNTM: one, two, three, four. Also pdfs at cspmt (vol one, two)

Nestle 1899 2nd edition (pdf)

Catalogues

(list of other catalogues) (BL: early printed Bibles)
Darlow & Moule, Historical Catalogue of the Printed Editions of Holy Scripture (London: BFBS, 1903-1911) (hathitrust)
E. Reuss, History of the Sacred Scriptures of the New Testament
E. Reuss, Bibliotheca Novi Testamenti Graeci (1872)
M.Vincent, A History of the Textual Criticism of the New Testament

Major Sites:

E-rara (rare books in Swiss Libraries)

Zentrales Verzeichnis Digitalisierter Drucke

Deutsche Digitale Bibliothek

Worth checking:
Online Books
Gallica
Early English Books Online
Early European Books
Eighteenth Century collections online