Guy Ramsay Fieri (US: /fiˈɛdi/ fee-ED-ee, Italian: [ˈfjɛːri]; né Ferry; born January 22, 1968) is an American restaurateur, author, and an Emmy Award winning television presenter. He co-owned three now-defunct restaurants in California. He licenses his name to restaurants in cities all over the world, and is known for hosting various television series on the Food Network. In 2010, The New York Times reported that Fieri had become the "face of the network", bringing an "element of rowdy, mass-market culture to American food television" and that his "prime-time shows attract more male viewers than any others on the network".

Fieri was born Guy Ramsay Ferry on January 22, 1968 in Columbus, Ohio, the son of Penelope Anne (née Price; born 1944) and Lewis James Ferry (1942–2024). Guy grew up in Ferndale in rural Humboldt County, California. During high school, he was a foreign exchange student in Chantilly, France, where he developed his interest in food and cooking.^{[dead link]}

Guy Fieri attended the University of Nevada, Las Vegas (UNLV), and graduated with a Bachelor of Science degree in hotel management in 1990.

Fieri began his association with food in grade school in Ferndale, by selling pretzels from his "Awesome Pretzel" bicycle cart at age 10 (he and his father built it) and washing dishes to finance a trip to France to study. Upon returning, he worked at the restaurant at the Red Lion Inn in Eureka, California, until he went to UNLV for college.

Soon after graduating from college, he worked as manager of Parker's Lighthouse, a restaurant in Long Beach, California. After three years in southern California, he became the district manager of Louise's Trattoria, managing six locations along with recruiting and training for the restaurants.

In late 1996, Fieri and business partner Steve Gruber opened Johnny Garlic's, a "California Pasta Grill" in Santa Rosa, California. A second location opened in Windsor in 1999, a third in Petaluma in 2000 or 2001 (since closed), and a fourth in Roseville in late 2008. They developed Tex Wasabi's (barbecue and sushi) in 2003 in Santa Rosa, adding a second location in Arden-Arcade near Sacramento in 2007 (which was rebranded as Johnny Garlic's and then closed). An additional Johnny Garlic's was opened in Dublin, California in 2011.

Fieri's first New York City restaurant, Guy's American Kitchen and Bar, opened in 2012 to brutal New York Times coverage by Pete Wells that Larry Olmsted of Forbes called "the most scathing review in the history of the New York Times", and "likely the most widely read restaurant review ever." Fieri, for his part, accused Wells, the nation's highest profile reviewer, of using Fieri's fame as a platform for advancing his own prestige. The restaurant's location in the highly trafficked Times Square enabled it to appear on Restaurant Business's list of the top 100 independent restaurants as ranked by sales for four years in a row. It closed at the end of 2017. In 2011, Fieri partnered with Carnival Cruise lines creating Guy's Burger Joint to sell Fieri's burgers fleet-wide. As of October 2017, there were 19 restaurants on Carnival's cruise ships, including some serving beer-and-BBQ, Guy's Pig & Anchor Smokehouse Brewhouse.

In April 2014, Guy Fieri's Vegas Kitchen and Bar opened on the Las Vegas Strip in Paradise, Nevada. In 2015, Guy Fieri's Baltimore Kitchen & Bar opened in Baltimore's Horseshoe Casino. In 2018, Fieri collaborated with Planet Hollywood founder Robert Earl to open fast-food chicken sandwich shop Chicken Guy! at Disney Springs in Walt Disney World.