The D-class (Zodiac III) lifeboat is a class of inflatable boat, operated between 1971 and 1996 by the Royal National Lifeboat Institution (RNLI) of the United Kingdom and Ireland. It was replaced operationally by the .
For more than 60 years the D-class has served as the workhorse of the RNLI Inshore Lifeboat (ILB) fleet. The D-class is one of the few RNLI types not to feature a rigid hull. The D-class was specifically designed as a light and highly manoeuvrable rapid response craft, especially suited to close shore work.