裸藻纲（Euglenophyceae）在生物分类学上是裸藻门（Euglenophyta）中的仅有的一个纲。

Euglenids (euglenoids, or euglenophytes, formally Euglenida, ICZN, or Euglenophyceae, ICBN) are one of the best-known groups of flagellates, which are Excavate Eukaryotes of the phylum Euglenophyta and their cell structure is typical of that group. They are commonly found in freshwater, especially when it is rich in organic materials, with a few marine, and endosymbiotic members. Most euglenids are unicellular. Many euglenids have chloroplasts and produce energy through photosynthesis, but others feed by phagocytosis, or strictly by diffusion. This group is known to contain carbohydrate paramylon.