Well, you've got London Calling, right?
Bad Religion- Against the Grain
Minor Threat- Complete Discography
Black Flag- Damaged
The Clash- The Clash
88 Fingers Louie- Back On the Streets*
*A little more modern, and not one of the usual "essentials," but I've been listening to it a lot and it's one of my all time favorite punk records.
"COLONEL KLINK, WHY HAVE YOU FORSAKEN ME?!"