Considered Switzerland's finest animal painter, Koller is rated alongside George Stubbs, Rosa Bonheur and Théodore Géricault.
While his reputation was based on his paintings of animals, he was a sensitive and innovative artist whose well-composed works in the "plein air" tradition, including Swiss mountain landscapes, are just as finely executed.
[5] He is considered, along with Frank Buchser and Gustave Eugène Castan [fr], to be one of the most important Swiss painters of the 19th century.
In 1830 his father, Johann Heinrich, was a butcher and brewer, who became the innkeeper at the "Schwarzen Adler" hotel, in the centre of the city near the river.
[8] After he left the Industrial School in Zurich, in October 1843, Koller began studying under the art teacher Jacques Schweizer, the portrait painter Johann Rudolf Obrist, and the landscape painter Johann Jakob Ulrich,[2] and took private painting classes with them.
Ulrich, who was a successful painter of landscapes and animals, influenced him further in his choice of themes during his artistic career.
[3] In 1845 he went to Munich where he worked with a group of artists called "the Schweizer", led by the Swiss landscapist Johann Gottfried Steffan.
At the Academy Koller formed friendships with the future Swiss symbolist painter Arnold Böcklin and the German classicist Anselm Feuerbach.
[2] At the Louvre he copied Netherlandish artworks of the 17th century and familiarized himself with the works of contemporary animal painters such as Rosa Bonheur and Constant Troyon.
Later he travelled to Munich, where he became acquainted with the landscape and animal painters Johann Gottfried Steffan and Friedrich Voltz.
Koller chose to allude to the St. Gotthard tunnel project, which Escher had championed, and eventually combined several studies to paint the Gotthardpost, or The Gotthard Mail Coach, showing one of the horse-drawn mail coaches, rendered obsolete by the opening of the tunnel.
After Koller's death, the Zürich Art Museum staged an exhibition of his works, including some from his earliest years, and various personal artefacts.
Switzerland in 2013 issued a commemorative 50-franc coin bearing a likeness of Koller's most well-known work, Gotthard Post.