A Heighliner was a starship used by the Spacing Guild to transport people and equipment across the known universe.
Guild Heighliners were usually immense in size, easily accommodating many thousands of passengers and the vast export of planetary goods.
Spacing Guild Heighliners could be used to fold space to travel vast distances across the universe in an instant. They were piloted by Guild Navigators and Steersmen.
Pictures of Heighliners
A Guild Heighliner (Miniseries)
heighliners -Illustration for the Dune encyclopedia by Matt Howarth
Heighliner as depicted in the Dune CCG
Heighliner in the 1984 Dune Movie
Heighliner Illustration by DB Ellis
Heighliners were not described in detail by Frank Herbert in his original Dune releases, however both the 1984 Dune Movie and the Dune Miniseries of 2000 show guildships as gigantic cylindric vessels.The Dune Encyclopedia however states that Heighliners were of globular shape.