The Dentrassi are a species from the Hitchhiker's Guide to the Galaxy universe, which are employed as catering staff on the Vogon's long haul fleets. They are described in the book as 'an unruly tribe of gourmands' and 'a wild but pleasant bunch'. Ford Prefect says that they are 'the best cooks and the best drink mixers' and also that 'they don't give a wet slap about anything else'.
The Dentrassi 'really hate the Vogons', so much so that, in an attempt to annoy them, will always help hitch hikers on board Vogon spacecraft, and serve sub-standard food to the Vogons.
The only physical description provided in the book is that at least one Dentrassi was 'a huge furry creature'. In the TV series, their appearance seems humanoid, with large facial features.