Portland Sea Dogs
- Location: Portland, ME
- League: Eastern League 1994-present
- Affiliation: Florida Marlins 1994-2002; Boston Red Sox 2003-present
- Ballpark: Hadlock Field
- Famous Alumni: Josh Beckett, Luis Castillo, Livan Hernandez, Charles Johnson, Kevin Millar, Jonathan Papelbon, Brad Penny, Edgar Renteria
The Portland Sea Dogs began play in the Eastern League as an expansion club in 1994. After nine seasons as a Florida Marlins farm team, they became an affiliate of the Boston Red Sox in 2003. The Sea Dogs have advanced to the Eastern League championships four times in their history, losing the first three times before finally capturing a title in 2006.