Staff/Employees
Seasons 1–3
Bertram Cooper”Senior Partner
Alice Cooper”Senior Partner, Sec’y/Treasurer
Roger Sterling”Junior Partner
Donald Draper”Junior Partner
Account Team
Head of Account Services–Roger Sterling until October, 1960.
Starting November, 1960, Herman ‘Duck’ Phillips is Head of Account Services.
- Pete Campbell
- Mitch Sullivan–Media (was described as fat, bald & charmless, and having a hot wife)
- Ken Cosgrove
- Harry Crane–Media–promoted to Head of the Television Department
- Warren–shares an office with Harry
Research
- Dr. Greta Guttman
- George Pelham
Creative Team
Creative Director–Don Draper, made partner in October, 1960.
Creative Team
“Smitty” Smith (copywriter) and Kurt Smith (art). Kurt is a homo.
Art Department
- Salvatore Romano
- Frank (referred to in The Hobo Code)
- Marty Faraday
- Dwayne Davis
Copywriting
- Freddy Rumsen (fired in August 1962)
- Paul Kinsey
- Victor Manny (I think he’s copy)
- David Stubing… got fired (also, I’m only assuming he was copy)
- Peggy Olson, Junior Copywriter, as of November 23, 1960, Copywriter as of August 1962
Administrative
Joan Holloway–Office Manager
Secretarial
- Peggy Olson March/April 1960-November 1960
- Eleanor was Don’s secretary before Peggy
- Alison who wears blue panties, is on Don’s desk for Season 3
- Jane Seigel–replaced Lois as Don’s secretary, off Don’s desk August 1962
- Ginger (Babylon; cuts her own hair)
- Hildy is Pete Campbell’s secretary
- Joyce is Duck’s secretary
Switchboard
- Marge (trying to lose weight)
- Ivy (blonde, likes flowers)
- Lynette (bath salts)
- Lois Sadler–by February 1962 was Don Draper’s secretary, then back to switchboard, then was Paul’s secretary until Guy Walks Into An Advertising Agency
- Donna (in Hobo Code) (maybe not? Maybe a secretary in Babylon.)
Mailroom
- David Cohen
Unknown positions
- Dale (Account ) (not married)
- Frank Birmingham (probably Account–brings in a lot of accounts)

Not Sterling/Cooper employee, but Hollis the elevator operator is a fascinating observer/commenter in the wings.
And don't forget the janitor who saw Peggy and Pete schtupping in Pete's office that morning.
Don't forget the guy who runs the lunch cart. He's in "Ladies' Room", where a pompous Paul Kinsey buys Peggy lunch and gives her an over-inflated tour of Sterling Cooper. He's also in"Red in the Face", where Peggy and Pete have an erotic episode in his office over Pete's weird hunting narrative. The lunch-cart guy sells Peggy a ham sandwich and a cherry danish. He also witnesses. He's replaced by the lunch-cart lady who witnesses Joan grilling Paul about the foray into Cooper's office in "The Gold Violin".
I get the impression that Mitch Sullivan is in charge of Media, and that explains why Harry doesn't seem to like him–Harry thinks that he could do his job better.
Also, don't forget Burt Peterson, from (I think) Accounting, who both Pete and Duck couldn't stand.