| Alt-Bichelsee Castle | |
| Built: | about 1250 |
| Type: | hill castle |
| Condition: | ruin |
| Location: | Bichelsee-Balterswil |
| Coordinates: | 47.4474°N 8.9174°W |
| Map Type: | Canton of Thurgau#Switzerland |
| Code: | CH-TG |
Alt-Bichelsee Castle is a ruined castle in the Swiss Canton of Thurgau in the municipality of Bichelsee-Balterswil.