| TRILOGY | A series of three related works |
| SPUTNIK | Name for the world's first satellite, launched by the Soviet Union on October 4, 1957, and the name of any of a series of three artificial Earth satellites. (7) |
| TIANGONG | Name for any of a series of three Chinese space stations, the first of which was launched on September 29, 2011. (8) |
| TRIADS | Groups, sets or unions of three related things; or, in music, chords consisting of three notes (6) |
| PUNIC | The ... Wars were a series of three conflicts between Rome and Carthage (5) |
| RURITANIA | Imaginary country in a series of three 1890s novels by Anthony Hope (9) |
| SAGA | The Forsyte _, a series of three novels by John Galsworthy (4) |
| PAPANDREOU | Surname of three related prime ministers of Greece, the last serving from 2009 to 2011 |
| ALOU | Last name of three related baseball All-Stars |
| TIEIN | Product exploiting a related work in another medium |
| GRANDTOUR | Collective name for the series of three professional road cycle races including the Giro d'Italia and Vuelta a Espana (5,4) |
| LORD | The ___ of the Rings film series of three epic fantasy adventure films |
| THENAKEDGUN | Series of three films based on the sitcom Police Squad! |
| MILLENNIUM | Series of three novels by crime writer Stieg Larsson |
| DENTAL | Tooth-related, ... work |
| YOSEMITEFALLS | What, in eastern California, is the series of three waterfalls: the Upper Fall, 438 metres high; the |
| OEDIPUSREX | Sophocles Greek tragedy, it's the second in his series of three Theban plays (7,3) |
| PUNICWARS | Series of three conflicts fought between the Roman Republic and the Carthaginian empire (5,4) |
| THEGEICOCAVEMEN | Offended parties in a long-running series of 3-Down |
| IASIMOV | With 12-Down, 1995 Hugo Award winner for Best Related Work |
