Alexander Guagnini or Alessandro Guagnini (1538 – 1614), was an Italian chronicler from Verona. He served in the Lithuanian military in Vitsebsk (which was part of the Grand Duchy of Lithuania).

He is known for publishing the book titled Sarmatiae Europeae descriptio, quae Regnum Poloniae, Lituaniam, Samogitiam, Russiam, Masoviam, Prussiam, Pomeraniam... complectitur', usually translated as "A Description of Sarmatian Europe" (printed in Cracow, 1578). It contained descriptions of the countries of Eastern Europe (history, geography, religion, traditions, etc.) in Latin.

It is argued that he was not actually the author of the book, but rather stole a manuscript of the Chronicle of Poland, Lithuania, Samogitia and all of Ruthenia from Maciej Stryjkowski, who was his subordinate. Stryjkowski protested before King and his claims were recognized in 1580, but the book continued to be printed under Guagnini's name and was even translated to Polish language. An expanded edition appeared in 1611.

The chronicle included portraits of Lithuanian dukes for the first time. Despite the images being purely fictional and having nothing to do with actual dukes, anachronistic clothes and weapons, and that some of the images illustrated multiple people, the portraits highly influenced future depictions of the Grand
Dukes of Lithuania. To this day they remain the most popular portraits used in many history books.

Copies of the book are preserved, among other places, in the library of Vilnius University and in the Francysk Skaryna Belarusian Library and Museum (London).

He died in Krakow.