Castle in Byki, Medieval castle in Piotrków Trybunalski, Poland.

The Bykowski Castle in Byki is a late-Renaissance structure of stone and brick on an elongated rectangular plan running north-south. Its central section and one tower rise three storeys, the rest two, with two towers preserved at the corners. Renaissance window surrounds and portals survive, along with a slightly projecting gate tower with a passage, barrel vaults and wooden ceilings inside.

The exact construction date is unknown; the first written record, from 1604, concerns a rebuilding by Jan Stanisław Bykowski, voivode of Sieradz, for the Jaxa-Bykowski family of the Gryf coat of arms. After World War II the castle passed to the State Treasury and was thoroughly restored in 1959–1964 to designs by Eugeniusz Budlewski and Henryk Jaworowski, then given over to educational use.

The castle was the seat of the Jaxa-Bykowski family of the Gryf coat of arms, and its name comes from the village of Byki, now within Piotrków Trybunalski. Each year the grounds host the Piotrkowskie Targi Ogrodnicze "Pamiętajmy o Ogrodach" and the ROL-SZANSA agricultural trade exhibition.

The castle stands within the remains of a historic park in Byki, now part of Piotrków Trybunalski. It was empty throughout 2024, and a major renovation announced for early 2025 is to give it conference and exhibition functions. The grounds host the annual Piotrkowskie Targi Ogrodnicze "Pamiętajmy o Ogrodach" and the ROL-SZANSA agricultural exhibition.

The castle was registered as a monument on 16 September 1967, and its surrounding park followed on 31 August 1983. The park is a remnant of the historic grounds that once framed the residence of the Jaxa-Bykowski family of the Gryf coat of arms.