Harry Potter: Ranking Every Death Eater From Worst To Best
2. Barty Crouch Jr.
Though Severus Snape may be one of the greatest double agents the Wizarding World has ever seen, Barty Crouch Jr. was better. He managed to hide his secret allegiance from everyone including his father, a high ranking wizard in the Ministry of Magic.
In fact, if it wasn't for Igor Karkaroff turning his back on the Death Eaters and giving up his fellow disciples, he could have carried on working for the Dark Lord in secret for who knows how long. Even once he had been exposed, Barty Crouch Jr. still found a way to secretly work for Lord Voldemort.
Disguised as Mad-Eye Moody, Crouch managed to orchestrate Harry entering and successfully navigating the Triwizard Tournament, ultimately leading the boy who lived to his master, allowing the Dark Lord to return in his physical form. Such was his commitment to his performance, he somehow managed to master Alastor's voice, something which no one else using polyjuice potion in the movies could manage.
As useful and reliable as he was to Voldemort however, there was just one more that the Dark Lord could count on even more so than Barty Crouch Jr.