Ondrej Krivanek is at the forefront of pioneering advances that have endowed electron microscopy with the ability to image and analyse matter atom-by-atom. His early work improved an existing electron microscope and used it to image directly, for the first time, the atomic structure of defects in semiconductors. He next designed several instruments for electron energy loss spectrometry (EELS). These are now used by hundreds of researchers worldwide. He also co-authored an EELS atlas, which is a standard reference source for spectra. Recently, he designed and built a practical aberration corrector, thereby reaching a goal that had remained elusive for some fifty years. His novel microscopes are now able to map chemical elements in solid samples with atomic resolution and single atom sensitivity.