Abraham Ortelius appeared before the end of 1572; twenty-five editions came out before Ortelius' death in 1598; and several others were published subsequently, for the atlas continued to be in demand till about 1612. Most of the maps were admittedly reproductions (a list of 87 authors is given in the first "Theatrum" by Ortelius himself, growing to 183 names in the 1601 Latin edition), and many discrepancies of delineation or nomenclature occur. Wikipedia
The definitive Wikipedia entry for Abraham Ortelius. Wikipedia is the biggest multilingual free-content encyclopedia on the Internet. en.wikipedia.org/wiki/Abraham_Ortelius
It is less well-known that the University Library also has a large collection of atlases from Antwerp by Abraham Ortelius. cf.uba.uva.nl/en/collections/maps/ortelius/
We specialise in atlas maps by Ortelius (1527-1598), which appeared in his atlas Theatrum Orbis Terrarum . This was the first "modern" atlas published. orteliusmaps.com/