Angelo Bartlett "Bart" Giamatti (April 4, 1938 - September 1, 1989) was the President of Yale University, and later, the 7th commissioner of Major League Baseball in the United States. Giamatti is best remembered for overseeing the banishment of popular baseball player Pete Rose from the sport for his gambling infractions in 1989.

He grew up near Mount Holyoke College, in South Hadley, Massachusetts, where his father, Valentine Giamatti, founded the departments of Italian and Spanish languages and literatures. He also collected translations of Dante's Divine Comedy. His mother, Mary Claybaugh Walton, was the daughter of Helen (Davidson) Walton and Bartlett Walton, who attended Andover and Harvard College. His paternal grandfather, Angelo Giammattei (so spelled) emigrated from Italy through Ellis Island in about 1900. Bart graduated from South Hadley High School, and while President of Yale, served as a Trustee of Mount Holyoke College.

A. Bartlett Giamatti attended Andover and Yale. He was tapped by Scroll & Key, and graduated magna cum laude in 1960, marrying Toni Smith that same year. Toni Smith Giamatti taught English for more than twenty years at the Hopkins School in New Haven up until her death in 2004.

Of their three children, Marcus Giamatti, Paul Giamatti, and Elena Giamatti , two have become actors. In the movie Sideways a photograph of the younger Miles Raymond (Paul Giamatti) with his late father is really a picture of Paul and Bart Giamatti.

Bart stayed in New Haven to receive his doctorate in 1964. He became a professor of English at Yale University, an author, and master of Ezra Stiles College at Yale. He spent a brief period teaching at Princeton, but was at Yale for most of his teaching life. When his tenure as Stiles master ended in 1972, he was so popular that his students wanted to honor him with a present. Giamatti told them he wanted a joke gift and they got him a moosehead (from a yard sale), which was ceremoniously hung in the dining hall. As the new master took over, Giamatti told him in a serious tone, "I have only one solemn duty to convey to you. Take care of my moose."

He served as President of Yale University from 1977 to 1986. He was the youngest President of the University in its history. He served on the Board of Trustees of Mount Holyoke College for many years, participating fully despite his Yale and baseball commitments.

His lifelong interest in baseball (Giamatti was a die-hard Boston Red Sox fan) came into play when he became President of the National League in 1986, and later Commissioner of Baseball in 1989. Giamatti, whose tough dealing with the Yale's union favorably impressed Major League Baseball owners, was unanimously elected to succeed Peter Ueberroth as commissioner on September 8, 1988.

One of his main acts was the banishment for life of Pete Rose from baseball for betting on the sport and associating with known gamblers, detailed in the Dowd Report. Just a year earlier while still serving as National League president, Giamatti had suspended Rose for 30 games after Rose shoved umpire Dave Pallone on April 30.

While at his vacation home in Martha's Vineyard, Giamatti died rather suddenly of a massive heart attack at the age of 51, only eight days after banishing Rose. Bart Giamatti had only been the commissioner of baseball for 154 days.

James Reston, Jr. notes, in his book , that Giamatti suffered from Charcot-Marie-Tooth disease, an inherited neuromuscular disease affecting peripheral nerves.

|- style="text-align: center;" | width="30%" |Preceded by:
Peter Ueberroth | width="40%" style="text-align: center;" |Commissioner of Baseball
1989 | width="30%" |Succeeded by:
Fay Vincent

|- style="text-align: center;" | width="30%" |Preceded by:
Chub Feeney | width="40%" style="text-align: center;" |National League president
1986–1989 | width="30%" |Succeeded by:
Bill White

Books:

• A. Bartlett Giamatti, The Earthly Paradise and the Renaissance Epic (1966)
• James Reston, Jr., Collision at Home Plate: The Lives of Pete Rose and Bart Giamatti (1991)
• Anthony Valerio, A Life of A. Bartlett Giamatti: By Him and About Him (1991)