Lemmer may refer to:
- Lemmer (Dutch: De Lemmer), a town in the municipality of Lemsterland (province of Friesland), in the Netherlands
- Lemmer (surname)
- Lemmer (whaling), a person who dismembers (butchers) a whale
- Moths
- Lemmeria, a genus of the family Noctuidae
- Acronicta lemmeri or the impressive dagger moth
- Catocala lemmeri or the graceful underwing
- Hypagyrtis lemmeri or the esther moth
- Lithophane lemmeri or Lemmer's noctuid moth
- Zale lemmeri or the gray spring zale