Trafalgar ancestors / The National Archives, June 2005

http://www.nationalarchives.gov.uk/trafalgarancestors/
"The National Archives in the UK have launched a new database for people to see if their ancestors were at the Battle of Trafalgar."

There are about 18,000 people listed in the database, and as many as one-third of them may be from outside the British Isles. You can search them by last name, or use the advanced search by approximate age, ship name, or rating/rank. (Possible top tip)