The Programmer is an unknown student from the anime Angel Beats. He is revealed to exist when Yuri, the leader of the SSS,
decides to get to the root of what is causing malevolent creatures known as Shadows to manifest in the World.
The Programmer is widely credited with having created:
- the Angel Player program
- The AI
- The Shadows
It is likely that he created the Angel Player program, as it existed before Kanade Tachibana entered the Afterlife.
It's almost certain that the AI was made by the Programmer, when he states that he is "simply obeying the rules" when asked what he is doing with the computers from PC Room 1.
Once love began to take hold in the World, after
The AI would have activated the Shadow program, also manufactured by the Programmer, to begin wiping out the SSS, Guild, and NPCs.
Now, the Programmer's background is one of mystery. It's a long story, so I'm going to take a leaf out of the Wikia's book here (with some minor edits).
The Programmer's real name is unknown. But like Otonashi, he was never supposed to have entered the Afterlife, but somehow ended up there anyway.
During his time in the Afterlife School, he fell in love with an unnamed girl who disappeared when her regret was fulfilled. Unwilling or unable to accept that, he decided to wait for her to return, which from the Afterlife School rules would require her to:
- Die during her teenage years (13 to 17 or so for a 4 year gap)
- Have a heavy regret
If the girl lived an average of 85 years and reincarnated each time, there would be a 4/85 (teenage years)*9.83/1000(Japan death rate )*1%(Ad hoc chance of heavy regret)=~0.0004% every reincarnation. Each failure to hit this chance would lead to 85 years of waiting. A 10% chance to see her again would require 2.125 million years.
The above calculations do not consider that the majority of the death rate is actually from the elderly rather than from teenagers.
As expected, the amount stunned Yuri, due to the massive time required to be spent waiting. The AI explained that The Programmer lost his grip on sanity after waiting so long, and decided to create a program to turn himself into an NPC.
As The Programmer felt that people who had resolved their sadness should not clutter the Afterlife School (much like patients should be discharged when they are cured rather than staying in the hospital), he created a program that kept track of the amount of love in the Afterlife School world. When the amount of love exceeded a certain amount, a "cleaning" program would be activated where NPCs would be changed into Shadows, which would in turn target humans and forcibly change them into NPCs, thus resetting the world into one where no humans existed.