Question: During Payback (2016) which current United States Champion wrestler was defeated by Roman Reigns?

Context paragraphs:
Payback (2016): Payback (2016) was a professional wrestling pay-per-view (PPV) and WWE Network event, produced by WWE.  It took place on May 1, 2016, at the Allstate Arena in the Chicago suburb of Rosemont, Illinois.  It was the fourth event in the Payback chronology.  Eight matches were contested at the event, with two being shown on the pre-show.  In the main event, Roman Reigns defeated AJ Styles to retain the WWE World Heavyweight Championship.  Critics gave mixed reactions for the event and mocked WWE for promoting the event as the start of a "new era" despite employing several storylines they have been using since the late 1990s.

Ron Killings: Ronnie Aaron Killings (born January 19, 1972) is an American professional wrestler, actor and rapper.  He is signed to WWE under the ring name R-Truth performing on the Raw brand.  Killings is a former one time United States Champion and a one time Tag Team Champion as R-Truth, and a two time Hardcore Champion under the ring name K-Kwik.  Between 2010 and 2011, Killings headlined five WWE pay-per-view events; three times in world title contention.

Soulman Alex G: Alex Gibson is a professional wrestler better known as "Soulman" Alex G.  He is one of the two trainers who trained former WWE United States champion Montel Vontavious Porter and former NXT Tag Team champion Konnor.

1987 Little League World Series: The 1987 Little League World Series took place between August 25 and August 29 in Williamsport, Pennsylvania.  The Hualien Little League from Hualien, Taiwan, defeated the United States Champion Northwood Little League of Irvine, California, in the championship game of the 41st Little League World Series.

Jack Carkeek: Jack Carkeek, (January 22, 1861 – March 12, 1924) was an American Cornish champion wrestler, from Rockland, Michigan United States.  His parents were from Cornwall, United Kingdom.  He met many wrestlers in his career.  He died March 12, 1924 in Havana, Cuba.

NWA Mountain Empire Championship: The NWA Mountain Empire Championship was originally created to replace the NWA Smoky Mountain Television Championship.  On March 24, 2011; Chase Owens defeated Jason Kincaid to become the first champion.  On August 19, 2017; at ReGenesis, promoter Tony Givens announced that NWA Smoky Mountain Wrestling was leaving the NWA thus the promotion was changing their name to Innovate Wrestling and the NWA Mountain Empire Championship Championship was officially retired as a result.  Toby Farley defeated Timmy Lou Retton to become the Interim Innovate Wrestling United States Champion.

Adeline Gray: Adeline Gray (born January 15, 1991) is a three-time world champion wrestler from United States.

JAPW Light Heavyweight Championship: The JAPW Light Heavyweight Championship is a championship in the Jersey All Pro Wrestling promotion in the United States.  Being a professional wrestling championship, it is not won via direct competition; it is instead won via a predetermined ending to a match or awarded to a wrestler because of a wrestling angle.  It became official title on December 5, 1997 when Rik Rachet defeated Chino Martinez in a tournament final to crown the first champion.  It was retired on September 15, 2006 when the New Jersey State Championship was re-activated.  Kazarian remained champion as a result.  Prince Mustafa Ali became the new champion after the title was re-activated.  The current champion is Archadia, who is in his first reign.  There have been 27 reigns by 21 wrestlers with six vacancies.  One of those vacancies came when Billy Reil was injured.

Orlando Jordan: Orlando Mason Jordan (born April 21, 1974) is an American-Australian semi-retired professional wrestler.  He is best known for his tenure in World Wrestling Entertainment (WWE), where he was a one-time United States Champion.  He is also known for his stint with Total Nonstop Action Wrestling (TNA).

A.J. Styles: Allen Neal Jones (born June 2, 1977), best known by the ring name AJ Styles (also stylized as A.J. Styles), is an American professional wrestler who is signed to WWE performing on the SmackDown brand, where he is the current United States Champion in his second reign.  He has long been regarded as one of the world's best professional wrestlers.

Supporting paragraphs: Payback (2016) A.J. Styles
Answer: A.J. Styles