NICER Observations of Neutron Stars and Black Holes

The NICER X-ray astronomy instrument, operating on the International Space Station since June 2017, has significant new capabilities for the study of accreting neutron stars and black holes, including large effective area, low background, superb time resolution, and excellent low-energy X-ray response. I will review some early results on both black holes and neutron stars from the NICER mission, including observations of black hole transients, ultraluminous X-ray pulsars, accreting millisecond pulsars, and thermonuclear X-ray bursters.