Disambiguation; There are 8 Groups with the same name.

1) A death metal band from Poland started in 2004;

2) A rave/happy hardcore group from  The Netherlands, popular in the Mid-Nineties.
Critical Mass was formed in 1994 by Ed Bout and Dave Hasselaar.
ID&T records (the centre of hardcore at that time) wanted a live act. At the beginning both producers where the act by themselves but not much later they integrated the singer Ludmilla Odijk and rapper Danny Haenraets alias MC Energy.
At the end of 1995 they got a hit with "Dancin' Together". In 1996 3 big hits followed: "Burnin' Love", "Believe In The Future" and "Happy Generation". In 1997 another single followed called "Together In Dreams". In 1999 the group tried again with a trance single called "In Your Eyes", it became a clubhit. "In Your Eyes" and "Together in Dreams" (both being eurotrance tracks, and not happy hardcore) were picked up by Byte Records. But even Byte failed to make Critical Mass succeed;

3) A contemporary catholic rock band started in 1997 by David Wang. Their first demo recording, Faith Looks Up,  won Best International Group and Best Modern Rock/Alternative Album honors from the United Catholic Music and Video Association. Their second album Completely received Best Rock Album of the Year at the Canadian Gospel Music Association’s Covenant Awards.  The success of Completely resulted in the group being invited to be in the liturgical celebrations at World Youth Day 2002 in Toronto. The band was given the honor of performing at both the Papal Welcoming Ceremony and at the Papal Vigil, the latter of which was seen by the 600,000 in attendance and on international television. Grasping for Hope in the Darkness was released in 2004. It won Best Rock Album honors at the Covenant Awards. Their cover of the Kansas classic, Carry On Wayward Son was nominated for Best Rock Song.  In 2007, Critical Mass released a live praise and worship effort called Celebrate. This album was nominated for 6 United Catholic Music and Video Association Awards. In 2009, Critical Mass released "Body Language", an album based on Pope John Paul II’s Theology of the Body. This is one of the first Christian rock albums to ever deal so explicitly with the topics of sex, love and communion, in a Catholic Christian context;

4). A ska band which was formed in 1992 in the San Francisco Bay area. Before that, the members had played in various bands over the prior decade, including The Noise, Basic Radio, JFK, Missing Link, Chill Factor and Elephant Men.
Critical Mass, the Ska-Group, has played shows with The Skatellites, Reel Big Fish, Save Ferris, Less Than Jake, Bow Wow Wow, The Toasters, The Untouchables, Dave Wakeling, The Skeletones, Let's Go Bowling, Jump With Joey, The Scofflaws, Big Bad Voodoo Daddy and countless others. They won Best Ska group at the 1998 Wammies, a 1998 California Music Awards (Bammie) Nomination for Outstanding Ska Artist (as well as performing at the Awards show), and The 1996 TicketMaster National Showcase; 

5) Progressive Metal brand from Australia, they've formed in 1989 and released their only album in 1992 - Holy Wars. After one year they split up;

6) Progressive Metal band from Århus, Denmark. Released their first album Wasted Sentence in 2009;

7) Early US punk rock band from Miami. First punk band from Florida to release a record, "Silver Screen" 7" in 1978.

8) Avant-garde / experimental jazz  /  free jazz project from Georgia. First album was released in 2014 and the band immediately got noticeable fame inside the underground jazz scenes of Russia and Georgia. The band formed in 2013 in  Moscow, Russia and consists of 2 members:

Guram Machavariani - Guitars 
Irakli (Kvazi) Sanadiradze - Drums, percussion