Arngeir is the leader of the Graybeards.
Story[]
Teaching Cock the way of the voice[]
In The Moose-Born, Cock Nibbler meets Arngeir to learn from him as advised by Jarl Balgruuf. As part of his training, Cock performs all of the weird things Arngeir has him do like shouting (thu'um) and running really fast (whirlwind spirit). Arngeir accepted his efforts and had Cock retrieve the Horn of Jurgen Windcaller.
Peace Council[]
In order to convince Jarl Balgruuf to open the BDSM chamber for the dragons, Cock Nibbler has Arngeir conduct a peace council. The peace council would force a ceasefire between the Imperials and the Stormcloacks while Whiterun is left defenseless dealing with dragons. Cock invites all of the Skyrim leaders to attend the peace council, which, to Cock's bewilderment, will be held at High Hrothgar. Once everyone makes the hike up to High Hrothgar, Cock sits in at the meeting with the leaders of Skyrim. Arngeir is quite pessimistic about the meeting, which Cock Nibbler berates as having a poor attitude and negotiation skill on Arngeir's part. (Fellowship of the C**k Ring)
Translating the pancake recipe[]
In Honey, I Killed the Kids, Crotch Guzzler visits High Hrothgar to get somebody wise to translate the pancake recipe for him. However, Arngeir suggest he talk to Paarthurnax.