Hammerjacks Concert Hall and Nightclub was a large concert hall in downtown Baltimore through the 1980s and into the 1990s owned by Louis J. Principio Jr. The club attracted many big-name national acts, but also showcased many rising stars in the music world. The bands ranged from punk, glam, and heavy metal acts most commonly associated with the venue (e.g., Guns n Roses, Kix, Ratt, Skid Row or Extreme) to pop (e.g., Badfinger) and alternative rock groups (e.g., Goo Goo Dolls). The club was often frequented by hard core patrons and musicians donning big hair, leather, lace, spandex, and heavy makeup, and was considered a "hard rock shrine."  Hamerjacks, however, attracted audiences with other attire as well. It was torn down on June 12, 1997 to make way for M&T Bank Stadium parking lot. Hammerjacks was billed as "The largest nightclub on the east coast."
The club was featured in the John Waters' 1994 film Serial Mom, with grunge band L7 playing the band Camel Lips. It was the location where Kathleen Turner's character Beverly Sutphin was arrested for murder. Interior and exterior views of the club have been featured in music videos, including the band Kix. An image of a sign for the club appeared on the Iron Maiden album "Somewhere In Time".
As of July 2, 2011, the Trademark Electronic Search System (TESS) listed five different records pertaining to the trademark "Hammerjacks." The only active application for the trademark was by Hammerhouse Designs LLC. The attorney of record was Lawrence E. Laubscher, Jr. The resident agent was listed as Kevin Butler. The application for this trademark was filed January 27, 2011 and published for opposition April 19, 2011. The other records pertain to adandoned applications and registrations. Official merchandise can still be purchased on the Hammerjacks' website, which is operated by Hammerhouse Designs. In 2010 Kevin Butler acquired the lapsed trademark. Kevin Butler has made extensive plans and investment to open a new 57,000 sq. foot nightclub nearby the old location.  
- "Louis J. Principio Jr., Hammerjacks' founder." Obituary (no author listed) (November 21, 1991). Baltimore Sun. Retrieved December 21, 2010.
- Piccoli, S. (1997, May 18). "Just take those old rockers off the shelf upstart label specializes in second chances for recording artists eclipsed by pop trends." Sun Sentinel (Fort Lauderdale), p. 1.D
- Considine, J. D. (November 10, 2000). "New Hammerjacks is not an 80s place. Nightclub: The music and bar venue, lost to the Ravens' parking lot, rises again. Hammerjacks' third incarnation." Baltimore Sun. Retrieved December 21, 2010.
- Morgan, Jon (April 01, 1997). "Moag sets deadline for Hammerjacks Stadium authority expects deal next week or takeover." Baltimore Sun.Retrieved December 21, 2010.
- Mirabella, Lorraine, Hiaasen, Rob, & Sessa, Sam (May 24, 2006). "Baltimore nightclub is to close Saturday: Hammerjacks, heavy metal, rock icon, has been sold to developers." Baltimore Sun. Retrieved December 21, 2010.
- "Somewhere In Time - Cover Details". The Iron Maiden Commentary. Maverick. Retrieved 13 April 2013.
- Maryland Department of Assessments and Taxation. Retrieved July 2, 2011.
- The Trademark Electronic Search System (TESS), United States Patent and Trademark Office. Retrieved July 2, 2011.
- Smith, Mark R. (6 March 2012). "Lightning Set to Strike Upon a Revived Hammerjacks". The Business Monthly. Retrieved 13 April 2013.
- Maza, Erik (11 November 2011). "Hammerjacks Comeback Planned New Trademark Owner Wants Spot by Baltimore Casino". The Baltimore Sun. Retrieved 13 April 2013.