Saving the universe from a threat, lots of shiny weapons, a hidden headquarters, black clothing? This almost sounds like the PPC, but it is, in fact, Men in Black, which has to its universe three movies, an animated series, and some comics.
The basic premise of MiB is saving the Earth from alien threats while keeping the existence of aliens a secret to the general public.
The progenitor of the popular MiB franchise is The Men in Black, a comic series created by Lowell Cunningham in 1990-91. The comics showed a secret organisation dedicated to suppressing and monitoring paranormal activity on Earth while preventing the general public from learning of the existence of aliens. Its agents are referred to by letters, and sever all ties with their former lives (all their records are deleted) upon joining the agency. One agent went rogue after realising that the agency was keeping aliens hidden so that they could manipulate and reshape the world. However, the film franchise seems to have deleted this plotline altogether, and the Marvel comics that accompany the films reflect that.
The film franchise Men in Black is closer to the PPC in terms of comedic elements. Instead of suppressing alien activity, the film version of MiB merely monitors aliens and prevents them from posing any significant threats to human life on Earth. According to the first film, the organisation was founded in the mid-1950s as a government agency devoted to making contact with extraterrestrials. Earth was made, upon first contact with alien species in 1961 outside New York City, into an apolitical planet where alien species may take refuge, provided they adapt to a human-appearing lifestyle and do not raise the suspicions of the native population. The MiB were then turned from a badly funded government organisation to an independent entity funded by patented alien technologies that they appropriate from their extraterrestrial refugees, including things like liposuction and Velcro. They are devoted to monitoring aliens who have taken refuge on Earth, and intervening when the public is made aware of alien activity or when aliens threaten the Earth.
This has led to, naturally, one threat to the Earth per movie released, the most recent one involving a heavy amount of time-travel in order to resolve. The films follow the exploits of Agents Jay (no, not that Agent Jay) and Kay (alternatively styled 'J' and 'K') and their efforts in stopping said alien invasions.
MiB is, due to its nature as a secret organisation involved in monitoring extraterrestrial life, often crossed over with continua such as The X-Files, Doctor Who/Torchwood and The Avengers. Often, crossovers with The Avengers will imply that Phil Coulson and Agent Kay are related.
It is also crossed over with continua touching on anything supernatural, with the explanation that they don't just cover aliens.
Sues in this continuum are likely to be agents themselves as well as romantic interests of Agents Jay and Kay, despite regulations against fraternising amongst agents.
MiB and the PPCEdit
Due to the numerous similarities between the MiB and the PPC, missions in this continuum are likely to be extremely sensitive ones. After all, this continuum is home to the neuralyzer, a key tool for both MiB and PPC agents. MiB HQ also contains a de-neuralyzer, which implies that any neuralyzed memories of PPC agents are in danger of being recalled, should the canon characters choose to use it in that manner. Breaking into MiB HQ to de-neuralyse a PPC agent (or for any other reason) is a Very Bad Idea, since MiB HQ is probably extremely well-equipped to deal with things like random intruders popping in to use their tech.