Hans Ditlev Christian Martens, was a Danish-German painter.

Martens was trained as a painter in Kiel; then went to the Copenhagen Academy of Fine Arts as a student of CW Eckersberg.

Ditlev Martens arrived in Rome on 31 December 1825 without funds. Here he immediately sought out Bertel Thorvaldsen , who took care of him. Shortly afterwards, he began a sketch of the interior of Thorvaldsen's studio, a work that documented the papal visit to Thorvaldsen. He drew and painted diligently, especially interiors from Rome's churches and monasteries, but also veduter, inspired by his teacher CW Eckersberg's time in Rome. Thorvaldsen bought several of these works to support him.

During his stay in Hamburg from 1837 to 1842 , Martens received many orders and became a wealthy man. His home was destroyed during the city fire in 1842, and shortly afterwards he probably traveled to Copenhagen. Here he attached himself to the portrait painter N.P. Holbech, whom he knew from Rome. Martens was for some years busy decorating Holbech's home in Kronprinsessegade. He left the city in poverty and died in his hometown of Kiel in 1864.