Patrologiae cursus completus, which includes Patrologia Latina (and Supplementum) and the Patrologiae Graecae
Patrologia Latina (PL) includes works of the Fathers from Tertullian in 200 CE to Pope Innocent III in 1216
Patrologiae Graecae (PG) (1857-1866) includes works of the Fathers in the Greek language. There are 161 volumes.
There are two fantastic indexes on the Latin Patrology and the Greek Patrology
Other great indexes on the Greek Patrology and the Latin Patrology
Further archives on PG and PL
Fantastic indexed directory by author of PG, with edited PDF (!!!)
Here’s a complete TOC for volumes 1-18 of PG
Here’s a detailed and thoroughly complete TOC of PG and TOC of PL
Corpus Christianorum (CC) link
Critical texts for early Christian authors, out of Belgium (Brepols) from 1953-1973, designed to replace Migne with new critical texts.
Corpus Scriptorum Ecclesiasticorum Latinorum (CSEL) link
Late antiquity and early middle ages, covers Latin writers.
Sources Chrétiennes (SC) link
Series of critical editions with French translation/commentary focused on the sixth century or earlier.