David Hilbert, named after German mathematician was the first period-23 oscillator to be discovered. It was found by Luka Okanishi on November 24, 2019 based on a partial result by praosylen.
It consists of two copies of an engine, itself consisting of a B-heptomino being hassled by two unusual catalysts and a block, supported by a known period-agnostic beehive shuttle mechanism.

David Hilbert was voted for Pattern of the Year 2019 and won the first place.