| Thicker Than Water | |
| Publisher: | Big Finish Productions |
| Series: | Doctor Who |
| Number: | 73 |
| Featuring: | Sixth Doctor Mel Bush Evelyn Smythe |
| Cover: | Thicker than Water (Doctor Who).jpg |
| Director: | Edward Salt |
| Producer: | Gary Russell Jason Haigh-Ellery |
| Executive Producer: | none listed |
| Production Code: | 7CU |
| Preceding: | Evelyn: after Industrial Evolution Mel: Catch-1782 |
| Following: | The Wishing Beast & The Vanity Box |
| Length: | 1 hr 37 mins |
| Date: | September 2005 |
Thicker Than Water is a Big Finish Productions audio drama based on the long-running British science fiction television series Doctor Who. It is a sequel to the earlier audio play Arrangements for War.
It is three years since the Sixth Doctor helped repel the Killoran invasion of Világ, and he brings a new friend, Mel, to meet an old one. Evelyn Smythe, his former companion is now married to Principal Triumvir Rossiter. But Evelyn has made political enemies, among them her own stepdaughter Sofia, and the reunion takes a deadly turn when Evelyn and Mel are kidnapped.