The Tortoise Trainer is an oil on canvas painting completed by Osman Hamdi Bey in 1906. Measuring 221.5 by 120 cm, the work was created during the later period of the artist's career. The painting is notable for its large scale and for its detailed depiction of both human and animal figures.

Modern researchers have identified the tortoises in the scene as Testudo graeca ibera, a variety of the Spur-thighed Tortoise. The painting depicts a man in Ottoman dress, wearing a long red robe and a turban, standing in a sparse interior with cracked walls. He holds a traditional ney flute and a stick, while several tortoises move slowly on the floor around him. The composition uses a vertical format, with the figure dominating the space and the tortoises arranged at his feet.

The light is soft and diffuse, highlighting the textures of the man's clothing and the shells of the tortoises. The palette is dominated by warm reds, ochres, and earth tones, with careful attention to detail in the rendering of fabric and surfaces. The Tortoise Trainer is one of Osman Hamdi Bey's most recognized works and has been widely exhibited and reproduced. Sold in 2004 for US$3.5 million, the painting is now displayed at the Pera Museum in Istanbul.

The work is often discussed in the context of late Ottoman art and the artist's interest in themes of tradition and reform. Its reception has contributed significantly to the reputation of Osman Hamdi Bey as a leading figure in the history of Turkish painting.