UFC 129: St-Pierre vs. Shields was a mixed martial arts event held by the Ultimate Fighting Championship on Saturday, April 30, 2011 at Rogers Centre in Toronto, Ontario.

The event was the sixth that the UFC has hosted in Canada and the first mixed martial arts event in Ontario since the sport was legalized in the province in August 2010. The Toronto event was originally titled UFC 131 by the promotion, but later changed to UFC 129 as its early 2011 schedule started to fall more firmly into place.

It was the largest UFC event in North American history and coincided with a two-day UFC Fan Expo at the Direct Energy Centre. UFC officials had originally planned for the Rogers Centre to be configured to hold 42,000 fans for UFC 129. The UFC put those tickets on sale to UFC Fight Club members in a special pre-sale on February 10, 2011, selling nearly all of them. They released and sold more tickets the following day to UFC newsletter subscribers in a second special pre-sale. UFC 129 then sold out when tickets went on sale to the general public on February 12, with officials scrambling to up the number of seats to 55,000. Selling out all 55,000 tickets for gate revenues exceeding $11 million, the event shatters both MMA attendance and gate records in North America.

Dana White (born July 28, 1969) is the current President of the Ultimate Fighting Championship (UFC), a mixed martial arts organization based in the United States.

Born in Manchester, Connecticut on July 28, 1969, White grew up in Las Vegas, Nevada, Ware, Massachusetts and Levant, Maine. White is a passionate Boston Red Sox fan. During his youth, he bounced back and forth between Boston and Maine. He attended the University of Massachusetts Boston but did not finish; however, while there he did launch a boxing program for inner-city youth.

White has a background as an aerobics instructor. In 1992, White established Dana White Enterprises in Las Vegas. He conducted aerobics classes at three gyms in the Las Vegas area and began managing MMA fighters Tito Ortiz and Chuck Liddell.

While working as a manager, White learned that Semaphore Entertainment Group, the parent company of the UFC, was looking for a buyer for the UFC. White contacted childhood friend Lorenzo Fertitta, an executive at Station Casinos, and a former commissioner of the Nevada State Athletic Commission. Within a month, Lorenzo and his older brother Frank bought the UFC, with White installed as its president. White currently owns about 9% of Zuffa, LLC, the entity the Fertitta brothers created to own and manage the UFC.

Lyoto Carvalho Machida (Portuguese pronunciation: [liˈotu maˈʃidɐ]; born May 30, 1978) is a Japanese-Brazilian mixed martial artist from Salvador, Bahia, Brazil who fights as a light heavyweight in the Ultimate Fighting Championship. He is a former UFC Light Heavyweight Champion and is currently ranked as the #6 light heavyweight fighter in the world by Sherdog, MMAWeekly and Yahoo! Sports.

Machida was born in the city of Salvador as the third son of the highly ranked head of the Brazilian branch of the Japan Karate Association, Shotokan karate master Yoshizo Machida. Yoshizo moved to Brazil from Japan when he was 22 years old. There he met and married Lyoto's mother, Ana Claudia. Growing up in Belém, Lyoto began training in karate at the age of three and earned his black belt at the age of thirteen. He also began training in sumo at twelve and Brazilian Jiu-Jitsu at fifteen. He won a number of amateur karate tournaments, including the 2001 Pan American Karate tournament.

He was the runner-up in the 2000 Brazilian Sumo Championships in the 115 kg division. As an adult, he became Brazilian Champion twice under Taylor Swanson, and placed second in the South American Championship. He defeated American black belt Jiu-Jitsu fighter Rafael Lovato Jr. at L.A. Sub X. In addition to his sumo and karate achievements, he has a college degree in Physical Education. Lyoto's brother, Chinzô, is a Shotokan vice-champion (Australia 2006), losing only to number-one ranked Shotokan master Koji Ogata. Lyoto and Chinzô fought in a Karate Final 10 years ago in which Lyoto gave Chinzô a cheek scar that still exists today. His other brothers include Kenzo Machida, a TV journalist for one of Brazil's biggest TV stations, Take Machida and adopted brother Francisco Machida.

Randy Duane Couture (pronounced /koʊˈtʊər/; born June 22, 1963) is an actor, retired American mixed martial artist, collegiate and Greco-Roman wrestler. During his tenures in the Ultimate Fighting Championship (UFC), Couture became a three-time UFC Heavyweight Champion, two-time UFC Light Heavyweight Champion, an Interim UFC Light Heavyweight Champion, and was the UFC 13 Heavyweight Tournament Winner. Couture is the first fighter to hold two UFC championship titles in two different divisions (heavyweight and light heavyweight). Couture has competed in a record 15 title fights. He holds the most title reigns in the UFC with five. His last fight with Lyoto Machida marked his 24th fight in the UFC, the third most amount of fights in the UFC (Tito Ortiz is first with 26 and Matt Hughes is second with 25). Couture is one of the first members of the UFC Hall of Fame. He is the only person over the age of 40 to have won a UFC championship fight, having done so four times.^{[citation needed]}

Couture was an Olympic wrestling alternate and has lived in Corvallis, Oregon, throughout much of his career, where he served as an assistant wrestling coach and a strength and conditioning coach for Oregon State University. He established Team Quest with Matt Lindland and Dan Henderson, a training camp for fighters, based out of Gresham, Oregon, and headed by coach Robert Folis. In 2005, Couture moved to Las Vegas, where he opened his own extensive chain of gyms under the name Xtreme Couture. He currently trains at his Las Vegas-based gym. Couture partnered with Bas Rutten in the opening of Legends Gym in Hollywood, California.

Steven Frederic Seagal (born April 10, 1952) is an American action film star, producer, writer, martial artist, guitarist and reserve deputy sheriff. A 7th-dan black belt in Aikido, Seagal began his adult life as an Aikido instructor in Japan. He became the first foreigner to operate an Aikido dojo in Japan.

He later moved to the Los Angeles, California, area where he made his film debut in 1988 in Above the Law. By 1991, he had starred in three successful films, and would go on to achieve greater fame in Under Siege (1992), where he played Navy SEALs counter-terrorist expert Casey Ryback. However both On Deadly Ground (1994, which he directed) and Under Siege 2: Dark Territory (1995) did poorly in theaters. During the later half of the 90s, he starred in three more theatrical films and a direct-to-video The Patriot. Aside from Exit Wounds (2001) and Half Past Dead (2002), his career shifted almost entirely to direct-to-video films (often low budget productions and shot in Europe or Asia). Between 1998 to 2009, he appeared in a total of 22 of these. At the age of 59, he returned to the big screen as Torrez in the 2010 film Machete. As of 2011, he's currently busy with the third season of his reality show Steven Seagal: Lawman.