Placentia may refer to:
- Palace of Placentia, an English royal palace
- Placentia, Italy, a Roman city known today as Piacenza
- Placentia, Newfoundland and Labrador, Canada
- Placentia Bay, body of water
- Placentia, California, United States
- Placentia station, proposed train station in Placentia
- Battle of Placentia (disambiguation)
- Placentia Bay
- , the name of two ships of the Royal Navy
See also
- Placencia, Belize
- Plasencia, Extremadura, Spain
- Plentzia, Basque Country, Spain
- Piacenza (disambiguation)
- Plaisance (disambiguation), a French word
- Not to be confused with Placenta