Largest bacterium ever found is surprisingly complex.

@article{Sanderson2022LargestBE,
  title={Largest bacterium ever found is surprisingly complex.},
  author={Katharine Sanderson},
  journal={Nature},
  year={2022}
}

References

A centimeter-long bacterium with DNA contained in metabolically active, membrane-bound organelles

TLDR
Candidatus (Ca.) Thiomargarita magnifica is characterized, a bacterium that has an average cell length greater than 9000 micrometers and is visible to the naked eye, and contains compartmentalized genomic material and disrupts conceptions of microbial morphology.