There are numerous artists known as Hammer:

1. British heavy metal/NWOBHM band
2. Polish thrash/heavy metal band
3. Argentinian thrash metal band
4. Italian heavy metal band
5. Bay-area groove rock band
6. Finnish NSBM band
7. Japanese hardcore band
8. South Korean nu-metal band
9. British Grime emcee
10. 2 albums ("Black Sheep" & "Hammer") released by Jan Hammer in the late 1970s under the name Hammer.
11. Hammer was also used as a pseudonym by MC Hammer.

1) Hammer was a NWOBHM band formed in 1982 under the name Holland. They recorded and released 'Early Warning' as Holland, but were thereafter forced to change their name after being threatened with legal action by a Canadian band bearing the same moniker. After settling with Hammer, they released the LP 'Contract With Hell' in 1985. The lineup consisted of vocalist Marty "The Dog" Wilkinson, guitarists Bob Henman and Kenny Nicholson, bassist Graeme Hutchinson, and drummer Marty Day.

2) Hammer was a Polish oldschool thrash/heavy metal band founded in 1985. They released four albums (two in polish, two in english) and one split with Destroyer. Hammer consisted of Robert Köhler (vocals), Jarosław Kopała (vocals, guitar), Andrzej Szenajch (vocals, guitar), Jacek Osuch (bass), and Tomasz Klimczak (vocals, drums). Hammer broke up in 1993, and has since started playing with new lineup in 2002.

3) Hammer is a thrash metal band from Córdoba, Argentina.
Their current line-up is:
Gerardo Funes - Vocals, Guitar
Guillermo Cienfuegos - Guitar
Ismael Bernabei - Bass
Bruno Scotte - Drums
They released a three-way split in 1993.
They also released a demo in 1992 simply called "Demo '92" with 4 songs and one in 1993 called "Psycho Damage" with 6 songs.
Their only full length album, titled "No Way Out", was released in 1995.

4) Hammer is an Italian heavy metal band who originally formed under the name Hellrider. The lineup consists of Richard on bass, harmonica, and vocals, Christian on guitar, and Arlek on drums.

5) Hammer Was a Bay Area groove-rock combo comprised of singer John DeRoberts, guitarist Jack O'Brien, bassist Richie McBride, keyboardist Norman Landsberg, and drummer John Guerin. Formed in 1969, the group was quickly signed by legendary promoter Bill Graham to his fledgling San Francisco Records label -- their self-titled debut LP appeared in 1970, supported by a series of high-profile opening dates at Graham's Fillmore venues. Despite strong critical notices, Hammer failed to earn much commercial attention, and although a second album was recorded, it was never released and the band dissolved. While Landsberg later collaborated with the Pointer Sisters, Guerin went on to co-found the pioneering fusion unit L.A. Express

6) Hammer is a national socialist black metal band from Finland. Formed in 2004, the band consists of Ravenum - Drums and Guitars (Horna, Blutschrei) and Verflucht - Bass and Vocals (Alttari)

7) Hammer is a Japanese Hardcore band

8) 해머(Hammer) is a South Korean nu-metal band. The lineup consists of Wonki (guitars), Minsok (drums & programming), Namsoo (vocals), Kisok (bass) and Sehwoan (turntables & sampling).

9) Hammer is a UK Grime MC. Read more on Last.fm. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.