Many single-celled organisms, primarily prokaryotes, use binary fission as their primary mode of reproduction. Here are some examples:

* Bacteria: Almost all bacteria reproduce through binary fission.

* Archaea: Like bacteria, these single-celled organisms also reproduce via binary fission.

* Some protists: Certain protists, such as amoeba and paramecia, use binary fission for asexual reproduction.

While binary fission is the primary mode of reproduction for these organisms, it's important to note that some of them, like bacteria, can also engage in other mechanisms like conjugation for genetic exchange.