Robert Donald "Donny" Petersen (17 April 1947 – 12 December 2021) was a Canadian outlaw biker, writer, and alleged gangster. The author of 21 books, Petersen won the International Book Award in 2012, 2013 and 2014, and served as the national secretary and principal spokesman for the Hells Angels Motorcycle Club in Canada.

Petersen was born in Toronto to a middle-class family. In his late teens, he joined the Para-Dice Riders, an outlaw biker club based in Toronto. Petersen graduated from North Toronto Collegiate Institute. Petersen attended York University where he studied Urban Planning, but did not graduate.

Petersen began his career as a social worker in downtown Toronto. Accordingly, to the biography posted on his website, Petersen "then began working with drug induced problems in the early seventies hippie era". He was notably vague on whose "drug induced problems" he resolved or how. In 1973, Petersen opened Heavy Duty Cycles, which became one of the most successful motorcycle shops in Toronto. He also was a successful columnist on motorcycle-related topics with his writings appearing in both Canada and abroad in various magazines. Petersen rose up became the vice president of the Para-Dice Riders. Petersen's nickname as an young man was "Sleaze". One policeman stated in 2003 that Petersen was confrontational, saying: "Donny got right in the middle – he was at the forefront. He's got that streak. But these days you don't see it. It's well hidden now". Starting in 1992 and continuing right up to his death, Petersen wrote a monthly column entitled "Techline" in American Iron Magazine.

Petersen had no criminal record and in 1996 sued the Ontario Provincial Police (OPP) for their roadside stop policy for outlaw bikers, claiming that this was harassment. In the spring of 1997, he went to Havana as a guest of the Canadian embassy to work as a guest lecturer at the Havana Harley Riders Club. In September 1997, Petersen – who favored having the Para-Dice Riders join the Hells Angels – welcomed the Hells Angels national president Walter Stadnick to Toronto. In the fall of 1997, Petersen became the first outlaw biker to address the prestigious Empire Club of Toronto, which the journalist Jerry Langton noted was "...an honor normally reserved for heads of state and titans of industry". Previous speakers at the Empire Club included former U.S., president Ronald Reagan, the evangelist Billy Graham and the 14th Dalai Lama. Petersen was a successful and wealthy businessman whose many friends in Toronto's corporate elite included Gareth Seltzer, a well known Bay Street investor. Seltzer was also the president of the Empire Club at the time. Seltzer invited Petersen to speak at the Empire Club on the subject of being both a successful businessman and outlaw biker. Petersen's speech to a well-heeled crowd, which included some of the most wealthiest and powerful people in Toronto, was well received. Petersen's speech at the Empire Club represented a trend of the outlaw biker sub-culture becoming part of the mainstream of Canadian life. Sitting alongside Petersen at his table at the Empire Club were Charles Dubin, the former chief justice of the Ontario Court of Appeal, and Alan Borovoy, the president of the Canadian Civil Liberties Association.

In February 2000, Deanne Cunningham, the Ontario Minister of Training, Colleges and Universities, appointed Petersen to be the chief of a government committee assessing apprenticeship training for mechanics. Petersen was appointed to head the committee because of his "expertise and experience", with his membership of the Para-Dice Riders not being a handicap. Petersen personified the embourgeoisement of the Canadian outlaw bikers, going from having long hair and a shaggy appearance as an young man to becoming a businessman with trimmed hair and a 'respectable' appearance in his middle-age.

On 29 December 2000, Petersen joined the Hells Angels. At a ceremony at the clubhouse of the Hells Angels' "mother chapter" in Sorel-Tracy, Petersen burned his Para-Dice Rider colours and put on a Hells Angel jacket. Petersen became the national secretary of the Hells Angels and their principal spokesman, a role for which was selected for by Stadnick. When the Hells Angels held a convention in Toronto on 12 January 2002, Petersen bristled during a press conference at the suggestion that the Angels were a "gang" as he insisted that the Angels were merely a "motorcycle club". As a public relations move, Petersen had all of the Hells Angels attending the convention donate to the local food bank. The convention was crashed by Mel Lastman, the mayor of Toronto, who posted for photographs with the Angels and thanked them for bringing so much "business" to Toronto. As he posed for a photograph with Tony Biancaflora of the Angels, Lastman told the assembled journalists that the Angels were "fantastic" and were "a nice bunch of guys".

Petersen used the Lastman incident to argue to the media that the Hells Angels were not a criminal organization. At that the point, the media discovered that Petersen was still in charge of the Ontario government's apprenticeship program. The revelation that the Hells Angels national secretary was the director of the Ontario apprenticeship program caused much controversy, and led the Ontario government to fire Petersen. In a letter announcing his firing, it was stated that he was being terminated because of "...your association with the Hells Angels". Amid a blaze of publicity, Petersen sued the Ontario government, claiming his right to free association has just been violated. Petersen wrote in his lawsuit: "My membership in a motorcycle club has always been and continues to be an important part of my personal belief system in individual freedoms and defiance of arbitrary and unlawful authority". In December 2002, Petersen lost his case with the Superior Court of Ontario ruling that the government was justified in firing him.

Petersen, described as the unofficial leader of the Hells Angels in Ontario, was known for his "brash" style. Petersen pioneered Hells Angels stores that sold Angel-related merchandise and clothing, through notably none of the items on sale bore the Hells Angels winged death head logo or their name, instead saying 81 (H is the eighth letter of the Latin alphabet while A is the first). The "support gear" on sale had slogans such as "Support 81" and ACAB (an abbreviation for "All Cops Are Bastards") Petersen told the media about the stores: "Obviously, we want to make money off them. And we do make good money off them". Langton noted that Petersen's assertion about the profitability of the stores seemed to be correct as he noted that business was very brisk at the one Toronto Hells Angels store he visited with a massive number of Torontonians buying clothing, hats and other merchandise covered with the numbers 81. The embourgeoisement associated with Petersen was very typical of the Hells Angels by the early 21st century. The Canadian criminologist Steven Schneider noted in 2009 that the popular stereotype of the Canadian Hells Angels as shaggy, disreputable types with long hair and long beards living on the margins of Canadian society is not true and has not been for some time. Schneider described the typical Canadian Hells Angels in the 21st century as well dressed, well trimmed, clean-cut businessmen who drive luxury cars and live in affluent suburbs, stating the club now aims to project a 'respectable' image. Sher and Marsden described Petersen as "a smart, smooth-talking businessman who would eventually rise to the top of the Hells Angels hierarchy in Ontario. Petersen is now neat and proper, his trim, light-colored hair belying his fifty-four years".