Depends. At my parent's place in the Basque Country, 8:30-10:30 pm, depending on whether any one of us goes out or not (thursday is specially late, due to a pub drink/eat custom we call pintxopote). When I was living in Belgium, I used to have dinner around 7pm (get home at 6 from work, an average 1 hour cooking, dinner). Now in Ireland, working from home... I eat when I get hungry. I could eat dinner at noon.
As a side note, dinner times is not isolated matter. Countries who have dinner earlier have very light lunches and their dinner is the main meal of the day, while countries who eat dinner later have only very light dinner and have eaten an abundant lunch. In Belgium, I often had just a sandwich for lunch, which made me hungry by 7pm. Finally, regarding work habits, countries that have dinner early usually have a more compact work timetable, and (I think) longer commuting times. In Belgium, I had to take a 45 minute train ride to go from Gent (where I lived) to Brussels (where I worked) every day. Lunch break was short, so my goal was to have lunch fast so I would finish work fast and go home early. In the Basque Country, I always just walked to work, and I could easily take 2 hours lunch break where I would go back home to have lunch with my family/friends, watch a Simpsons episode with them, thoroughly disconnect and then have a fresh afternoon start. Thus the bigger meal and the late light dinner.