There are several bands with this name:

1) Ultra was a Hard Rock band from San Antonio, Texas from the mid- to late‑1970s. Their sound was a mixture of heavy Southern blues rock, psychedelic rock, and proto‑metal. The members were: Galen Niles (guitar), Larry McGuffin (guitar), Don Evans (vocals), Scott Stephens (bass), and Tom Schleuning (drums). All of the songs were written by Niles, McGuffin & Evans. Their recordings were compiled two decades later into the album «Ultra» by Monster Records in Texas.

2) Ultra (also recording as Rider) is also an English pop band, which was most successful in the late 1990s.

3) Experimental/noise US outfit Ultra (R. Stanford King, Wesley Mark, Jon Carlson), who creates deeply anxious collages of sound and voice in a mixture of fear and beauty. There are some places where they scream their faces off, but mostly it is the nature of the sounds themselves: hordes of insects, demonic sighs, electric buzzes, rumbles, creaking that gets under your skin and into your head, whether you want it to or not.

4) Ultra is a hip‑hop superduo consisting of NYC rappers Kool Keith and Tim Dog.

5) Ultra was a synth‑pop band from Latvia that existed around the late 1990s, conceived as one more Latvian‑language version of the locally wildly popular Depeche Mode. Obviously taking their name from that group's 1997 album Ultra.