The division's top scorer Phil Jevons was well shackled by the resolute Andy Crosby, and was well supported across the back by Butler and Ian Baraclough.
Yeovil made a pacy start and Terry saw Paul Musselwhite take a high ball in the box, with Nathan Stanton swift to step in and halt Way.
When Scunthorpe replied Chris Weale moved quickly out of his box to head away from Paul Hayes.
The Iron came close to opening the scoring after 17 minutes when Baraclough placed a corner to the penalty shot and Butler moved in to thunder a header over the bar, and then Liam Fontaine swept away a dangerous ball from Hayes.
Jevons was denied in the 26th minute, he got away from the home defence but he was just offside before netting.
The Glovers came back and Gavin Williams forced a fine save from Musselwhite and has the home side retaliated when in-form Hayes swept a snap shot over the bar.
After having the best of the opening half, Yeovil came under more pressure and Weale pulled off a fine reflex save to deny Richard Kell, while Peter Beagrie also went close.
Yeovil might have snatched the lead through Jevons but he slipped as he was about to shoot.
Scunthorpe struck the decisive blow in the 78th minute, when Butler powered home a header from Beagrie's left-wing corner.
Yeovil's protests that the ball hadn't crossed the line were of no avail as the assistant referee signalled a goal.
Three minutes later Kell hit the bar as Scunthorpe drove forward again, while Jevons might have snatched a point in the closing minutes but fired over from six yards.