Illa Martin (born Sybilla Kesselburg; 25 February 1900 – 6 August 1988) was a German dendrologist, botanist, conservationist and dentist.

She studied dentistry in Bonn, Würzburg and Freiburg and in 1935 married the dentist Ernst J. Martin, with whom she shared a practice in Kaldenkirchen.

Illa Martin tried to make the forest floor a correspondingly diverse area of flora, containing for example, the American wild ginger Asarum caudatum.

After her husband's death in 1967, Illa Martin saw that economic continuation of the Sequoia Farm was impossible and so sold the site in late 1969 with buildings at the College of Education Rhineland (now the University of Cologne).

[5] The couple had two sons and a daughter, including the author and songwriter Erik Martin and the legal expert Helge Breloer.