Ondrej L. Krivanek FRS (born Ondřej Ladislav Křivánek; August 1, 1950) is a Czech-British physicist resident in the United States, and a leading developer of electron-optical instrumentation.

He then took an unpaid leave of absence from Gatan to develop an aberration corrector for a scanning transmission electron microscope (STEM) in Cambridge UK, together with Niklas Dellby and others.

[10] Nion correctors delivered to Oak Ridge National Laboratory produced the first directly interpretable sub-Å resolution electron microscope images of a crystal lattice[11] and the first EEL spectra of single atoms in a bulk solid.

[12] Nion has since progressed onto designing and manufacturing whole scanning transmission electron microscopes that have produced many further world-leading results,[13] such as atomic-resolution elemental mapping[14] and analytical imaging in which every individual atom is resolved and identified.

[15] In 2013, Nion introduced a new design of a monochromator for STEM that allowed the first demonstration of vibrational/phonon spectroscopy in the electron microscope,[16] and can now reach 3 meV energy resolution at 20 kV.