Alexandre Girardet (22 May 1767, Le Locle - 15 June 1836, Neuchâtel) was a Swiss engraver, illustrator and watercolorist.
He was born to Samuel Girardet (1730–1807), a bookseller and publisher, and his wife Marie-Anne, née Bourquin. His siblings, Abraham, Charles Samuel, Abraham Louis, and Julie (1769-1817), also became engravers. He was married to Catherine, née Guion
The brothers all studied engraving together. In 1783, he moved to Paris, to join Abraham, and work under his direction. He signed his works, "A.-G. le jeune", to distinguish them from the two Abrahams. He also painted in oils and watercolors. Among his illustrations are those for the picture book, La Suisse Romande (the French-speaking parts of Switzerland).
In 1792, he and Abraham returned to Switzerland. Two years later, Abraham went back to Paris, and Alexandre took over his position as a teacher. Due to mental illness, he had to give up teaching in 1801. He eventually was forced to give up painting and most of his other activities.