Trypanosoma, Nortiluca, Monocystis and Giardia are all unicellular protists.
Trypanosoma gambiense is the single-celled, parasitic zooflagellate causing trypanosomiasis or sleeping sickness. Giardia or the 'Grand old man of the intestine' is a diplomonadid parasitic flagellate occurring in the intestine of man and other animals and causes giardiasis or diarrhoea (ie, very loose and frequent stool containing large quantity of fat).
Noctiluca is a marine, colourless dinoflagellate- It is a voracious predator and has a long, motile tentacle, near the base of which, its single short flagellum emerges.