Guillem Soler

Image:Portolan [chart of Guillem Soler (c.1380, Paris).jpg|thumb|Portolan chart of Guillem Soler, c. 1380 (BNF, Paris)]
Guillem Soler, sometimes given as Guillelmus Soleri, Guillermo Soler and Guglielmo Soleri, was a Majorcan cartographer of the 14th century.
Little is known of Guillem Soler. Documents establish his existence in Majorca in 1368, and that he was dead before 1402. Historians once believed him to be an Italian named "Guglielmo Soleri" who worked in Majorca, but has since been more confidently identified as probably of Catalan origin. Majorcan documents identify him as "Guillermi Solerii", citizen of Majorca, master instrument-maker and mapmaker.
Guillem Soler was one of the few non-Jews of the Majorcan cartographic school. A letter of 1387 by King John I of Aragon, written shortly after the death of the great Majorcan cartographer Abraham Cresques, seems to refer to Guillem Soler as a "Christian master" of "similar skill", capable of completing one of Cresques's unfinished maps.
Guillem Soler is the author of two significant portolan charts.

c. 1380 portolan, undated but signed "Guillmus Soleri civis maioricaru me fecit". This is currently held by the Bibliothèque nationale de France in Paris, France.
1385 portolan, dated and signed "Gujllmo soleij ciujs Maoicaru me fecit Año A nt, dñj Mccclxx.v", held by the Archivio di Stato di Firenze, in Florence, Italy.

Both are "normal portolan" charts, covering usual range, but contain some stylistic differences. The first is considered quite typical of the Majorcan school, geared to geographical depiction, with plenty of illustrations and inland details. The latter portolan seems more reminiscent of the Italian school - that is, more nautically oriented, nearly bereft of illustrations and with very few inland details.
Guillem Soler's c. 1380 chart gives probably the first depiction of the royal arms of England as quartered with the royal arms of France
Guillem Soler is also the possible author of a third piece, a recently discovered fragment of a Catalan chart, covering only a portion of the west Mediterranean. It is unsigned and undated, but believed to be prior to the other two known charts. It is privately held.
Guillem Soler is believed to be the father of Majorcan cartographer Joan Soler and through him ancestral to the later mapmakers Rafel Soler and Gabriel Soler. He might also be the grandfather of Rafel Lloret