The green cooler has become a recognizable part of Sam and Dean's personal belongings. It is a vintage Coleman cooler.
The specific cooler seems to be a model 5206, which was introduced in 1959 and 1960 and shortly thereafter discontinued, when Coleman introduced the full "Snowlite" line and began making them with a white base later in 1960.
Note: A similar cooler is seen is season 8, but they are slightly different models. We can tell this model was made between 1962-1964, because it has the diamond imprinted on top, but it has the "cam-latch" which was introduced in 1962. By 1963 all coolers were manufactured with it.
Also, Benny's cooler from 8.09 Citizen Fang is the same style as seen in 1.15 The Benders. Due to the red outline on the label of this cooler, we can tell that it was manufactured in Canada.
The cooler also featured in this video of Jared being doused in ice as part of a fundraising drive for ALS in August 2014 known as the ALS Ice Bucket Challenge.
1.15 The Benders
Green cooler belonging to the Bender family. It is the same model as the one Benny owns in season 8.
3.07 Fresh Blood
Dean sits on the cooler while Sam works on the Impala.
4.13 After School Special
Dean grabs some beers while they discuss their current hunt.
5.03 Free to Be You and Me
The cooler is seen inside for the first time. Dean digs out a bottle while talking to Raphael.
5.14 My Bloody Valentine
Dean grabs a beer from the cooler in the motel they're staying at as he and Sam talk about how Valentine's Day is Dean's favorite holiday.
5.17 99 Problems
The cooler is seen inside the Impala. Post helping the townspeople to take care of some demons, the boys grab a celebratory beer out of the backseat.
5.22 Swan Song
Dean grabs a beer for himself before talking to Sam, and the boys share a beer while contemplating the task ahead of them.
6.09 Clap Your Hands If You Believe...
Dean drinks a beer after (soulless) Sam refuses one.
7.12 Time After Time
Dean has his feet propped up on the cooler before getting himself and Sam some beers. Later, Sheriff Mills arrives to help Sam find his brother, the cooler staying supportively in the background, steady in this time of crisis. (Method Acting).
7.09 How to Win Friends and Influence Monsters
The cooler is brought inside, and Dean moves it closer to the sofa so he can enjoy a drink.
8.09 Citizen Fang
A green cooler similar to the boys' one appears in Benny's camp.
8.10 Torn and Frayed
A later model of the Coleman green cooler is seen in Rufus' cabin. These started to be made in 1961.
9.19 Alex Annie Alexis Ann
A similar model green cooler is seen in the vampire's house.
A green cooler can be spotted in the background of Daniel and Adina's campsite.
10.04 Paper Moon
Sam and Dean relax with some beers out by a lake, with the green cooler between them.
10.10 The Hunter Games
Claire hangs out with her new friends - the ax murderers. @TheGreenCooler says he was asleep during this scene.
10.15 The Things They Carried
Dean uses the green cooler to hold bottled waters, while Cole is attempting to sweat out the Khan worm.
The green cooler holds beer, smoothies and a decapitated head.
11.11 Into the Mystic
Dean has a beer and sits on the cooler while letting Sam finish digging up a grave.
11.13 Love Hurts
Sitting quietly over by the sink.
12.15 Somewhere Between Heaven and Hell
Gwen Hernandez grabs the cooler to use as a weapon against Ramsey, the hellhound.
15.20 Carry On
The cooler appears in Heaven outside of Harvelle's where Bobby and Dean share a couple of beers from the cooler.
1.01 Pilot (The Winchesters)
The cooler is in the Impala's backseat as Dean drives away.
- @TheGreenCooler on Twitter
- Interview with @TheGreenCooler] by Fangasm
- origin story of The Green Cooler by @TheGreenCooler
- The Wall Street Journal "Love of My Life | The Coleman Cooler" by Kevin Sintumuang