Maciej is a Polish given name, ethimological equivalent to lithuanian Motjejus. Its diminutive forms are Maciek, Maciuś. Maciej may refer to:
- Maciej Kazimierz Sarbiewski, Europe's most prominent Latin poet of the 17th century
- Maciej Miechowita, Polish renaissance scholar, professor of Jagiellonian University, historian, chronicler, geographer, and medical doctor
- Maciej Pałyszko, Polish hammer thrower
- Maciej Stachowiak, Software engineer at Apple Inc. and web standards chair and editor
- Maciej Szczęsny, Former Polish international football player
- Maciej Zamoyski, Polish nobleman
- Maciej Zaremba, Swedish journalist and author
- Maciej Żurawski, Polish football (soccer) player
Nameday according to Polish calendar on: 30 January, 24 February, 14 May