The Lackwit is a dragon mentioned only on the How to Train Your Dragon Books official website as Viking initiate, Clueless' Hunting Dragon.
No description or image is given for the Lackwit. It is, however, mentioned to be a Hunting Dragon, implying that it is not big enough to ride and probably the size of a dog.
Lackwits are described as being "very violent and unfocused".
- Clueless in the Hiccup and Friends Guide on the Official How to Train Your Dragon Books Website.
NOTE: As of Spring 2018, the official website has been redesigned and key information is no longer available.