Fourth Council of Constantinople : 869-870
This was the first council that was not recognised as canonical by either Protestants or Orthodox authorities.

General Councils
Article from the Catholic Encyclopedia, looking at the definition, place in church governance and short historical sketches of each council until Vatican I.

The Church in Crisis A History of the General Councils - AD 325 through AD 1870
Text of the 1960 book by Monsignor Philip Hughes giving an historical background and an account of the proceedings of all the main Catholic ecumenical councils until Vatican I.

The Ecumenical Councils of the Roman Catholic Church
A list of summaries of the main facts of each recognised council.

Vienne, Council of
Convened 1311-1312 dealing mainly with the Knights Templars.