If 'Dream Theater' had started in 1975 instead of 1985 they would probably be more well-known in their home country of the USA.Still, they are have an international following that rivals any Metal and Progressive band out there.  Many bands have claimed them as a major influence.  Guitarist John Petrucci is one of the most accomplished players out there.  Mike Portnoy is easily one of the most technically sound drummers, and vocalist James LaBrie has a range most would kill for.

They are labeled as a Progressive Metal band more in the vein of Queensryche, but unlike their fellow Americans, they got their start smack dab in the middle of the grunge scene,  They carried the scene for awhile until the International scene literally exploded with bands similar to their style.  Now countries like Italy, Germany, Sweden and Finland are full of Progressive Metal bands.

Vandan Plas actually started around the same time as Dream Theater, and have been credited as Germany's greatest Progressive Metal Band.