Warning: This article includes spoilers for the first four seasons of “Mad Men.”

The thing that keeps myself and others so captivated by “Mad Men” isn’t the (admittedly glacial) plot or even the gorgeous period costumes and set design that the notoriously fastidious executive producer Matthew Weiner micromanages to perfection. Instead, it’s the nuanced and indelible ensemble cast of characters that populate the world of Madison Avenue.

Here’s a rundown of the key players, whether you’re diving into the “Mad Men” canon for the first time or need a refresher before Sunday’s premiere.

Don Draper (Jon Hamm) — Brilliant ad man, creative director at Sterling Cooper Draper Pryce and “Mad Men’s” requisite brooding male antihero in the vein of Tony Soprano and Walter White. Don is a secret war deserter with a stolen identity, a divorced father of three, a philanderer and an alcoholic. He is forever defined by his pronouncement in the pilot episode that he’s “living like there’s no tomorrow … because there isn’t one,” and typifies Weiner’s version of the perpetually unattainable American Dream. Think Jay Gatsby transplanted 40 years into the future.

Betty Francis, formerly Draper (January Jones) — Don’s icy ex-wife, now remarried to a prominent local politician and possibly even more miserable and emotionally repressed now than she was in her first marriage. Though reviled by some “Mad Men” fans for her bitterness, her childish outbursts and her mothering style which can only be described as neglectful, Betty remains one of the most tragic and fascinating characters on the show.

Peggy Olson (Elisabeth Moss) ­— Once a timid, naive secretary, Peggy soon bloomed into a copywriting wunderkind, proto-feminist icon and a loyal student of her mentor, Don. Intelligent, creative, and self-assured, Peggy is a career girl ahead of her time. Peggy and Don have one of the most compelling and complex relationships of the series, as they’ve both helped one another through their most grueling respective emotional lows: Peggy when she gave her surprise baby up for adoption, and Don when he mourned the loss of his oldest friend.

Pete Campbell (Vincent Kartheiser) — Slimy, spoiled, ambitious and manipulative, SCDP account man Pete is somehow still one of the most bafflingly lovable characters on the show. Maybe it’s his penchant for eating cereal on the couch in matching pajama sets or his touchingly respectful relationship with his wife Trudy (Alison Brie), but we just can’t seem to help rooting for weasely Pete.

Joan Harris, née Holloway (Christina Hendricks) — The sexy, savvy and ultra-competent knockout of an office manager uses both her brains and her curves to keep the chaotic Sterling Cooper Draper Price offices in check. Once an unabashedly sexually active single woman on the prowl for a rich husband, Joan is now married to a failed surgeon who, aside from having raped her on at least one occasion, has now enrolled in the army and has deployed to Vietnam. Held back in her job by the misogynistic environment of Madison Avenue, the tragedy underlying Joan’s character is all the more present now that she’s fallen back into an affair with old flame Roger Sterling and is pregnant with, potentially, his child.

Roger Sterling (John Slattery) ­— Wisecracking vodka-loving SCDP founder, WWII vet and relic of an earlier age of advertising. Having inherited his job from his father, one of the founders of the original Sterling Cooper firm, Roger is complacent in his role as partner and fills his days by drinking, smoking, womanizing and fighting with his twenty-something-year-old trophy wife, Jane.

Megan Calvet (Jessica Paré) — Don’s beautiful French-Canadian secretary, and, as of the season four finale, his surprise fiancée. Don dumped his high-powered steady girlfriend Dr. Faye Miller after a whirlwind weekend romance in California, during which he fell in love with Megan’s willowy frame and her Maria Von Trapp-like skill with his kids.

Sally Draper (Kiernan Shipka) — The Drapers’ headstrong tween daughter who seems on the verge of a major rebellion against her mother Betty. Due to a combination of “Mad Men”’s stellar writing and Shipka’s startlingly mature acting chops, Sally defies the typical “whiny teenager” trope that brings down so many other shows (I’m looking at you, “Homeland”).

Lane Pryce (Jared Harris) — A delightfully stuffy British founding partner of SCDP and financial wizard, Lane brings a sense of continental dignity to the office.

Bertram “Bert” Cooper (Robert Morse) — The only surviving founding partner of the original Sterling Cooper firm and a founding partner of Sterling Cooper Draper Pryce. An eccentric, avid espouser of Randian Objectivism and a Japanophile, Cooper requires shoelessness in his office and adorns his walls with erotic Japanese art and samurai armor.

Printed on Friday, March 23, 2012 as: Meet the ad men from AMC's hit show 'Mad Men'