1. Ciliates: Characterized by the presence of cilia, short hair-like structures that beat rhythmically for movement and feeding. Examples include *Paramecium* and *Stentor*.

2. Flagellates: Possess flagella, long whip-like structures that propel them through their environment. Some flagellates are photosynthetic, while others are parasitic. Examples include *Trypanosoma* (causes African sleeping sickness) and *Giardia* (causes giardiasis).

3. Amoebas: Distinctive for their flexible bodies and use of pseudopods (temporary extensions of cytoplasm) for movement and engulfing food. Examples include *Amoeba proteus* and *Entamoeba histolytica* (causes amoebic dysentery).

4. Sporozoans: Non-motile, parasitic protozoa that form spores at some stage of their life cycle. They often have complex life cycles involving multiple hosts. Examples include *Plasmodium* (causes malaria) and *Toxoplasma gondii* (causes toxoplasmosis).