Hammerjacks was a music venue in downtown Baltimore which operated from 1977 to 2006. It was founded by Louis J. Principio III. The club attracted many big-name national acts, but also showcased many rising stars in the music world. The bands ranged from punk, glam, thrash and heavy metal acts most commonly associated with the venue (e.g., Guns N' Roses, Kix, Ratt, Skid Row, Extreme or Wrathchild America) to pop (e.g., Badfinger) and alternative rock groups (e.g., Ramones and 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."^[1] Hammerjacks, however, attracted audiences with other attire as well.^[2]

Hammerjacks initially operated from a converted rowhouse on 1000 S. Charles St, then moved to an old brewery building at 1101 S. Howard St in 1982.^[3] The building was torn down on June 12, 1997, to make way for an M&T Bank Stadium parking lot.^[4] Hammerjacks was billed as "The largest nightclub on the east coast."

In 2000, Hammerjacks reopened at 316-318 Guilford Ave, which had formerly been used as a car wash.^[2] It was then put under new management in 2004, and closed in 2006.^[5]