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Many in the business consider Mahoney a living legend. He currently owns and is the principal artist at the Shamrock Social Club on Sunset Boulevard in Hollywood, CA.  Mahoney started his work as a tattoo artist in Boston in 1977 (when tattooing there was illegal), where he was in the midst of the 1970s punk scene. He has stayed relevant and influential in the tattoo world ever since. He was a pivotal force during the 1980s black-and-grey movement, and has tattooed some of Hollywood's biggest names.
Mahoney has said he knew what he "wanted to do" with his life when he was fourteen and hanging around with this "little greaser gang" and stepped into Buddy Mott's Tattoo Spot in Newport, Rhode Island. He said he has always been attracted to the idea that tattoos are "art for the people", art for the everyday man or woman. His early inspirations included cars, choppers, and religious artifacts. He is most known for his black and grey work, and more specifically images of religious icons, old school collages, girls, bombs, and guns.
When Mahoney first became interested in tattoo art, it was during a time period "when you had to be an outlaw, or you had to be a real brave soul to get a tattoo." With today's ease of tattoo removal and creams to make the process less painful, some of that appeal is gone, he said.
Many artists have showed appreciation for Mark, one of them being singer and songwriter Lana Del Rey who has worked with the tattoo artist on two of her music videos.
A self professed people person, Mark creates a laid back atmosphere in his shop that celebrities appreciate. Here is a list of some of his celebrity clients:
- Steve Jones
- Lana Del Rey
- Johnny Hallyday
- Jared Leto
- Shannon Leto 
- Janina Richter
- Mickey Rourke
- Brad Pitt and Angelina Jolie
- Johnny Depp 
- Tim Gonzo Ryan 
- The Notorious B.I.G.
- Heather Locklear
- Britney Spears
- David Beckham
- Brooklyn Beckham
- Maya Lake
- Zoe Saldana
- Nicolas Sarkozy
- Nicole Richie
- Robert LaSardo
- Fearne Cotton
- Fred Durst
- Mike Dirnt
- Cheryl Cole
- Russell Brand
- Lady Gaga
- Danny Trejo
- Harry Styles, Louis Tomlinson, Zayn Malik and Liam Payne
- Anne Hathaway
- Kaan Berke Kalkan
- Lapo Elkann
- Marilyn Manson
- John Hendricks
- Jack Osbourne
- Ali Mahir Aksu
- Bob Wentworth
- James Tarrant
- Shemar Moore
- Unplanned America (Netflix documentary series: Season 2 Episode 4 "Marked Men")
- Inked (A&E TV series)
- Vanity Fair
- Swindle Magazine
- Skin and Ink Magazine
- Best tattoo parlors in Los Angeles
- Lana Del Rey's music video of "West Coast"
- Lana Del Rey's music video of "Shades of Cool"
- Sunset Strip (2012 documentary film)
- Blood Ties (2013 film)
- Black Mass (2015 film)
Children's clothing line
Mahoney also designs for a clothing line for children called babyeggi. This company has a charitable component, donating 20% of their net proceeds to "grassroots non-profit organizations dedicated to making the lives of children better, and to pass on the important principle of giving back to the community. "
- "Meet the High Priest of Hollywood Tattoo Artists". The Hollywood Reporter. Retrieved 2019-09-23.
- "Archived copy". Archived from the original on 2009-05-31. Retrieved 2010-02-20.CS1 maint: archived copy as title (link)
- "Shamrock Social Club, Where the elite and the underground meet". shamrocksocialclub.com. Retrieved 2019-09-23.
- "Archived copy". Archived from the original on 2010-02-17. Retrieved 2010-02-20.CS1 maint: archived copy as title (link)
- "Tattoo Blog » It's Mark Mahoney Time!". Tattooblog.com.
- "Gonzo | Tim Ryan | Host | TV Series | Unplanned America | SBS 2". Sbs.com.au. Retrieved 2018-12-16. CS1 maint: discouraged parameter (link)
- "MARK MAHONEY: SHAMROCK SOCIAL CLUB. - BCND". Badcopnodonuts.com.
- "Shamrock Social Club West Hollywood". Citysearch.com.
- "Archived copy". Archived from the original on 2011-07-08. Retrieved 2010-02-20.CS1 maint: archived copy as title (link)
- "Archived copy". Archived from the original on 2010-02-25. Retrieved 2010-02-20. CS1 maint: discouraged parameter (link) CS1 maint: archived copy as title (link)