Born probably at beginning of sixteenth century. When Gustavus, according to Act passed at Vesterås, 1527, established the Royal Archives, he employed Ludvigsson to collect all the old documents belonging to the various churches. These were then deposited in the Royal Archives. Ludvigsson also, by order of Gustavus, compiled a genealogical table of the old nobility of Sweden, that Gustavus might know what estates to claim. Under Erik XIV., as well as under his brother Johan, Ludvigsson held the post of secretary to the king. He died in 1594. As a writer he shows great industry and poor judgment. The _Collectiones_ comprises a continuation of Svart's chronicle to 1560, a chronicle of Erik XIV., and a compilation of the early Swedish chronicles from 1362 to 1522. Of these the chief is the continuation of Svart, which includes also Svart's chronicle slightly altered, and the whole of it was long supposed to be Ludvigsson's own work, though the name was erroneously spelt Rasmus Carlsson. The original MS. of this continuation of Svart is in the University Library at Upsala. The MSS. of Ludvigsson's other works are in the Royal Library at Stockholm. KARL IX. _Rim-chrönika_, ed. B. Bergius. Stockh., 1759. 4^o. This is a metrical chronicle, written by one of the sons of Gustavus Vasa, and containing one or two references to Gustavus. B. _Letters, Treaties, and other Documents._ The contemporary documents bearing on the Swedish Revolution number several thousand. Nearly all of these have now been printed except the following collections:-- _Gustaf I.'s registratur._ This consists of thirty-one MS. folios containing copies of the letters written by Gustavus throughout his reign, and is preserved in the Royal Archives at Stockholm. The letters are arranged in chronological order, each folio as a rule embracing the letters of a year. Nearly all the folios were compiled by the king's secretary in the course of the year which they represent, though some of them were not compiled till 1600 or even later; and portions of the contemporary folios, left incomplete at the time, are filled out by a later hand. Besides this collection, the _Registratur_ originally embraced fifteen folios of the king's letters to foreign powers, and some folios of his letters on the crown estates; but these are lost. The thirty-first volume of the extant portion of the _Registratur_ does not properly belong there, being a transcription of Claes Christersson's letters to Gustavus in 1558-1561. Of the _Registratur_, ten volumes have now been published, extending through the year 1535. _Gustaf I.'s acta historica._