First, Osama bin Laden. Then, the former Bosnian Serb general, Ratko Mladic. And let's not forget - because these things often seem to come in threes -- Bernard Munyagishari, a former Hutu militia leader in Rwanda, wanted on charges of genocide and crimes against humanity.
One of them is dead, the other two are now in custody. All three of them are alleged to have been responsible for the deaths of thousands of people in some of the worst atrocities of modern times.
What strikes me as remarkable about all three of these cases is how long after the events the alleged perpetrators were hunted down. Perhaps we should be less cynical when politicians and prosecutors tell us they will not rest until alleged mass murderers are brought to justice.
Bin Laden was killed nearly a decade after 9/11; Mladic was arrested yesterday morning, 16 years after the massacre of more than 7,000 Muslim men and boys at Srebrenica in 1995; Munyagishari was apprehended 17 years after the Rwanda genocide, during which he is alleged to have recruited, trained and led Interahamwe Hutu militiamen in mass killings and rapes of Tutsi women.
My guess is that the trial of General Mladic, if and when it happens, will receive a great deal more publicity than the trial of Bernard Munyagishari. Yet if media coverage were to depend on the scale of the alleged atrocity, it should by rights be the other way round.
Remember what happened in Rwanda. In just three months, an estimated 800,000 people were killed, in an organised pogrom allegedly designed to wipe out the country's minority Tutsis and moderate Hutus.
The indictment issued by the International Criminal Tribunal for Rwanda, based in Tanzania, lists five charges against Munyagishari: conspiracy to commit genocide, genocide, complicity in genocide, murder as a crime against humanity, and rape as a crime against humanity.
That's quite a charge sheet. But of course if the prosecutors are to succeed, they'll have to prove that Munyagishari himself was both involved in, and had "command responsibility" for, the appalling atrocities of 1994.
As for General Mladic, the same applies. We know well enough what happened at Srebrenica, but again the court will have to be satisified that the man in the dock was responsible in law for those thousands of deaths. The erstwhile political leader of the Bosnian Serbs, Radovan Karadzic, is already on trial in The Hague - I suspect the two men will not be given the opportunity to spend much time together.
I visited Srebrenica in 1996, just a year after the mass killings. It was empty and virtually silent, the sort of place where the sound of absent footsteps is louder than on any city street. I also visited Potoçari, the grim industrial complex outside the town, which had been the UN base - the supposed "safe haven" - where so many of the Bosnian Muslims met their deaths.
But let me be clear: nightmare memories of a 16-year-old atrocity do not mean that General Mladic is guilty of the crimes with which he is charged. Only the court can decide that.
As for Osama bin Laden, of course, there'll be no trial, and no opportunity to test the strength of the case against him. You may well take the view that he convicted himself out of his own mouth, with the audio and video messages he released after September 11, 2001. It's not my place to offer a judgment on that.
If, as President Obama insists, "justice was done" when bin Laden was killed in his Pakistani hideout, well, one day, perhaps justice will also be done in the cases of Ratko Mladic and Bernard Munyagishari.
A different kind of justice, maybe, but justice nonetheless.