John Francis "Jack" Donaghy (/ˈdɒnəɡi/ DON-ə-ghee) is a fictional character on the NBC sitcom 30 Rock, airing from 2006 to 2013. The character was created by series creator Tina Fey, and is portrayed by Alec Baldwin. He was introduced as the Vice President of East Coast Television and Microwave Oven Programming for General Electric. As Vice President, he serves as the protagonist Liz Lemon's (Fey) boss as well as her personal mentor. As the series progresses, their relationship develops and informs their respective storylines. Donaghy climbs up the corporate hierarchy to achieve his professional dream of leading General Electric as its president and chairman.

Donaghy's penchant for wealth, power, authority, conservative values, and social status has been acclaimed as a high point of the series and his characterization. Fey intended for the character to serve as an oppositional but complementary counter to Lemon, expressed through various gender, social, and power dynamics. Baldwin received two Primetime Emmy Awards, three Golden Globe Awards, seven Screen Actors Guild Awards, and one Television Critics Association Award for his portrayal of this character.

John Francis Donaghy had an unhappy and impoverished childhood in South Boston and in the fictional suburb of Sadchester, Massachusetts. When he was two, Jack's presumed father lured him to the edge of a swimming pool with a puppy and pushed him in the pool, and later abandoned his family. His mother Colleen Murphy Donaghy has nagged him his whole life, even blaming him for John F. Kennedy's death and for his father leaving. However, she was also devoted to her children. For example, it was noted that she had traded sexual favors with (the fictional) Frederick August Otto Schwarz III for Christmas presents for Jack and his siblings. Young Jack took to calling his collie "Pop" until the dog was accidentally run over by the mailman and intentionally left to die in the street by his mother. The dog had earlier been neutered, causing Jack to charge his mother with "cutting Pop's balls off." His mother even tried to send him to Vietnam when he was 12 to make a man out of him. He also played hockey, the piano and the flute as a child, prompting his mother to embarrass him by having him play "The Star-Spangled Banner" on said flute in front of the hockey team, which he also captained.

Due to his family's poverty, Donaghy began working at the age of 12, as a stevedore at the Port of Boston. He attended Princeton University on a handsomeness scholarship, where he played football and baseball for the Tigers, joined the Princeton Charter Club, played Maria in an all-male production of West Side Story, was a member of the "Twig and Plums" secret society, and was a classmate of Michelle Obama. In addition to the Amory Blaine Handsomeness Scholarship, his jobs during college included "the day shift at a graveyard, and the graveyard shift for the Days Inn"; working as a janitor at a primate laboratory; and a job for the linguistics department recording every word in the English language, to preserve the perfect American accent in case of nuclear war. He laments that his voice has been dragged into various things like Thomas the Tank Engine and Wu-Tang Clan songs. (This joke refers to Alec Baldwin's role as a storyteller for Thomas and Friends in the U.S., seasons 5 and 6. He was also cast in the role of Mr. Conductor in Thomas and the Magic Railroad in 2000.) Subsequently, the linguistics department sold his voice to GE for use in their microwaves. He later attended Harvard Business School, which he paid for by working as a Swan Boat operator, and where he was voted "Most" by his classmates.

Post-college, Jack worked as an intern for Senator Ted Kennedy, where Jack displayed an extremely liberal political world-view, even by the standards of a young Al Gore. At some point, though as yet unexplained, he underwent a complete reversal of his philosophy and became a conservative Republican. Jack participated in Hands Across America and at some point personally coined the phrase "what's the upside?" He confessed that Carly Simon's 1972 hit song "You're So Vain" was, in fact, written by him.

In the years after working for Kennedy, Jack "thrived" on fear, bow hunting polar bears, climbing Mount Kilimanjaro, once driving a rental car into the Hudson River to practice escaping, showering with Greta Van Susteren and overcoming a peanut allergy through sheer willpower. Jack once practiced martial arts under Chuck Norris, but they had a falling out after he switched to another dojo.

It is revealed in "Live from Studio 6H" that, as a young employee in the GE poisons division in 1986, Jack answered phones during a live telethon. During that broadcast, Tracy Jordan realized his talent for getting laughs as a performer. A 16-year-old Liz Lemon made a prank call, claiming to have been a nurse in the war who was impregnated by General Electric when he was Colonel Electric. Jack's loyalty to GE and his handsomeness impressed Don Geiss, who transferred Jack to the microwave ovens division. At some point, he also rotated through GE's plastics division, where he befriended the "brilliant plastics engineer/lesbian", Gretchen Thomas. After years of market research, he finally made his "greatest triumph" in the form of the Trivection oven, a product he created at General Electric, having first envisioned it while responding to Liz Lemon's prank call in 1986. It was on the strengths of the Trivection oven that, in mid-2006, he replaced recently deceased Gary to become Vice President of East Coast Television and Microwave Oven Programming.

Jack was the architect of bringing Tracy Jordan on board the NBC sketch show The Girlie Show, despite the objections of head writer/creator Liz Lemon and producer Pete Hornberger. Jack made sure that Tracy was the main star and ensured the show's name was changed to TGS with Tracy Jordan after bribing a focus group with pizza. Other shows that NBC purchases while he is an executive include MILF Island and Queen of Jordan.