From Discworld & Terry Pratchett Wiki
|Physical appearance||Kindly-looking, middle-aged, white-haired gentleman|
|Books||Men at Arms, Feet of Clay, Hogfather, Jingo|
|Cameos||The Last Hero, Night Watch, Making Money|
Lord Downey is the current Master of the Assassins' Guild, having succeeded Dr. Cruces. He was educated at the Guild School at roughly the same time as Lord Vetinari and, in his role as School Bully, gave him the insulting nickname of "Dog-botherer". Vetinari got his vengeance, in a quite interesting manner in Night Watch.
It is assumed that he's since changed, but there is no concrete evidence of it. With the passing of the years and the shifting of their relationship, it is entirely possible that "Dog-botherer", together with one or two other indignities inflicted at school, hangs unspoken in the air between them whenever they meet formally. Although Vetinari would be professional enough not to let this cloud any aspect of what is otherwise a perfectly pleasant and amicable working relationship, Downey may be uncomfortably aware, on these occasions, of their shared past and the jolly larks they participated in as schoolboys. Downey is certainly more than acceptably deferential to Vetinari during their adult meetings. This apparent good will extends to his Head Master's Address in Discworld's Assassins' Guild Yearbook and Diary 2000, when using 'our own, much loved, Lord Vetinari' as an example of an Old Sicarian in a position of great power and authority.
Downey is a highly skilled poisoner, and it is apparently very unwise to try one of his almond slices. He contributed his recipe for mint humbugs to Nanny Ogg's Cookbook, although Nanny and the publishers and their lawyers warned strongly against the inclusion of the arsenic. Downey is also implicated in the plot to frame Sam Vimes using a planted packet of arsenic. He was responsible for accepting the Auditors' contract to inhume the Hogfather, and knew that Teatime was the Assassin for such a specialised task.
Downey's elevation to the peerage appears to be fairly recent. In Men at Arms, where for most of the book Downey is second-in-charge to Doctor Cruces, he is plain and simple Mr. Downey. As Samuel Vimes points out to Lord Rust during a difference of opinion in Jingo "...there's a good few Lordships in this city created by the Patricians. Your friend Lord Downey, for one."
The inference is that Vetinari, for reasons of his own, or maybe to honour precedent, ennobled Downey on his accession to Master of the Guild of Assassins. (But what might the Patrician have wanted in return?)
Downey is also the author of The Noble Art, a book likely to cover topics of interest to assassins and includes a section on rules applicable to assassination within civilization. Downey seems to consider Rules (and style) one of the key things defining an assassin from a murderer or expensive thug. However it is also worth noting one of Lord Downey's sayings is 'No one became a great Assassin by always obeying the rules. Of course, no one ever became a great Assassin by disobeying the rules and getting caught, either.'
His name in the German-language Scheibenwelt is Lord Witwenmacher - the Widowmaker.