Public Enemy No. 1 (abbreviated as PEN1; pronounced /ˈpiːnaɪ/), also known as PENI Death Squad (or PDS), is a prison and street gang formed in Long Beach, California^[1] and now based in Orange County, California.^[5][6] In 2004, the California Department of Justice described PEN1 as "one of the most powerful and fastest-growing gangs inside and outside prison",^[4] and reported it had about 200 members statewide. The gang's main activities include identity theft, credit card fraud, and methamphetamine sales.^[7]

The Public Enemy No. 1 gang emerged from the hardcore punk scene in Long Beach, California during the 1980s.^[1][8] By the 1990s, however, PEN1's base of operations was in Orange County where the gang began recruiting white suburban adolescents and became involved in methamphetamine trafficking, prostitution and identity theft.^[1][8] The gang also formed ties with the Aryan Brotherhood and the Nazi Lowriders in the prison system.^[1][7]

One of the gang's founders; Donald "Popeye" Mazza, became a made member of the Aryan Brotherhood.^[9] Another founding member, Devlin "Gazoo" Stringfellow, was stabbed to death by two other inmates at California State Prison, Sacramento on January 10, 2018.^[10][11] In June 2022, Donald "Popeye" Mazza has pleaded guilty to racketeering and conspiracy charges in federal court.^[12][13]

The gang uses the numeric symbol "737" to indicate association with the gang. The numbers correspond to the letters P, D, and S on a telephone keypad. The initials stand for PENI Death Squad, another name for the group.^[14]

Members often mark themselves with tattoos of different acronyms for the gang. Designs commonly include the words "PENI", "PDS" or the numbers "737", and sometimes in the form of runes, such as "ᛈᛖᚾᛁ" (PENI) or "ᛈᛞᛋ" (PDS), from Germanic runic alphabets.^{[citation needed]}

Public Enemy No. 1 is heavily involved in identity theft, which is not a crime often associated with street gangs; most of the income from this is allegedly used to finance methamphetamine sale and other operations. Originally, the gang did this by raiding mailboxes and trash cans for personal information, but later used contacts inside of banks, mortgage companies and state motor vehicle departments in order to gain access to credit profiles. This has led to law enforcement officials requesting that their personal information be removed so that it can't be used by gang members to identify home addresses of police officers.^[8] Additionally, PEN1 is involved in drug trafficking, murder, assault, auto theft, burglary and property crime.^[3]

• The gang is featured in the TV documentary series Gangland, season 6, Episode 14: "Public Enemy #1".
• In the crime-thriller feature film Shot Caller (2017), stockbroker and family man Jacob Harlon (played by Nikolaj Coster-Waldau) causes a fatal DUI accident and is sentenced to prison, where survival requires him to get mixed in gang life and associate with PENI gang members, then joining the Aryan Brotherhood through his connection to them.