Cornelis van Dalem was a Flemish painter and draughtsman active in Antwerp in the middle of the 16th century and an important contributor to the development of landscape art in the Low Countries. Van Dalem introduced into landscape painting new themes, which he derived from his humanistic education, and searched for new ways of representing his themes.

Details about his life are scarce. He was likely born in Antwerp. His father was a nobleman originally from Tholen who had moved to Antwerp where he was operating as a cloth merchant. His father was active in the local Chamber of rhetoric 'De Olyftack' in Antwerp and was the chamber's dean in 1552–3. The van Dalem family was a cultured family. Cornelis and his older brother Lodewijk likely enjoyed a humanistic education and were both trained as painters with the obscure artist Jan Adriaensens. Cornelis commenced his training in 1543 and became a master in the Guild of Saint Luke in 1556. The same year married Beatrix van Liedekercke, a member of a wealthy family.

Despite being a member of the Guild of Saint Luke, Cornelis van Dalem only practiced painting as an amateur and he remained a merchant his entire career. He was independently wealthy and did not need to rely on his art to make a living. However, he regarded art as an important part of his life as is demonstrated by the way he decorated the facade of his Antwerp residence. Cornelis had the façade of his house decorated with a splendour not seen in Northern Europe. The façade had a relief of the goddess Pictura in front of an easel, of Minerva and Mercury as well the stone busts of Durer and Jan van Eyck with laudatory inscriptions.

Bartholomäus Spranger was a registered pupil of van Dalem from 1560 to 1564. Van Dalem appears not to have been concerned much about teaching Spranger the art of painting but more about ensuring that his apprentice kept his studio clean and tidy. At the end of his four years of apprenticeship, Spranger is said to have been frustrated about his lack of progress. Around this time there were also increasing rumours about the possible heretical leanings of the van Dalem household: it was said they never went to the Catholic Church but rather attended Protestant gatherings. These rumours appear to have forced the van Dalems to leave Antwerp and settle on a castle near Breda. Accusations of heresy were said to have been reiterated against Cornelis in 1571 and he may have given refuge to a radical sect of Anabaptists. He died in Breda in 1573.