Agent Phillip Jeffries
Recapitulation of what is known about agent Phillip Jeffries for future reference (from Fire Walk With Me movies):
He is played by David Bowie. We first see him (in FWWM The Missing Pieces) when he enters a hotel Palm Deluxe in Argentina. He asks the receptionist if there's miss Judy staying in the hotel. Receptionist answers "a young lady left this for you" and gives him an envelope. Jeffries goes upstairs to his room accompanied by a bellhop who's carrying his luggage, but disappears somewhere along the way.
Next we see Jeffries (in both FWWM and FWWM The Missing Pieces) appearing out of nowhere in the FBI building, visibly shaken, and walking into Gordon's office. Cooper and Albert are also present there. Jeffries says "I'm not gonna talk about Judy. We're gonna keep her out of it." Gordon asks him "Where have you been? You've been gone for two years."
Jeffries tells them: "I found something in Seattle at Judy's (the information where the meetings are). I've been to one of their meetings. It's above the convenience store. They sat quietly there for hours." Then we are shown the meeting. Man From Another Place and Bob are there, also the old lady (Mrs Tremond) and her grandson who Donna once met when she was delivering Meals on Wheels, and some other people. They are talking about Garmonbosia and the usual nonsense talk.
Then Jeffries says "The ring... the ring..." and also "1989!" (when he realizes it's not 1987 anymore and he somehow lost two years) and vanishes again from Gordon's office.
We then see Jeffries (FWWM The Missing Pieces) appearing again in that same argentinian hotel and the bellhop is asking him "Oh my God, Mr Jeffries, where did you go?"