The England midfielder struck an equaliser that saw the home side rescue a point after they had twice gone two goals behind.
Marouane Fellaini and Tim Cahill both netted from close range inside the first 25 minutes to leave the Holte End stunned.
John Carew then brought Villa back into proceedings with a powerful finish on 33 minutes but after the break Everton restored their two goal lead thanks to a moment of inspiration from Steven Pienaar.
But, Martin O'Neill's men showed their mettle as James Milner replied instantly and Barry levelled after Stiliyan Petrov was fouled in the area.
All credit must go to the Villa players and manager as they completed a spirited comeback made even more amazing by the fact that they had gone eight games without a win coming into the clash.
David Moyes must have told his troops that an early goal would unsettle the home faithful who have seen plenty of poor performances this season.
And the shrewd Scotsman got his wish as Zat Knight failed to deal with a ball in the box and Leighton Baines crossed for Belgian sensation Fellaini to slot in.
After a bright start Villa were on the ropes and they had no response as Everton took full advantage of more poor defending.
Aussie midfielder Cahill was the beneficiary as he was granted an easy finish after seeing his own header rebound off the crossbar.
The Everton fans were in ecstasy. It was reminiscent of Villa's great early start at Goodison Park in December.
Just as Everton failed to cope defensively in that game, Villa struggled against every attack.
Dolls
Knight and Curtis Davies looked like a pair of China dolls who were liable to break at any moment. Both lacked the nous and knowledge of experienced absentee Martin Laursen. This sort of defensive display just wouldn't have happened under his stewardship.
With the home fans cajoling their side forward, Villa were under pressure to find an immediate response.
But they looked devoid of ideas and the midfield was suffering from a lack of movement up front. That is with the exception of Carew, who was winning everything and giving his marker a torrid time.
True to his terrace chant Carew was on fire. And it wasn't long before his constant hassling of the back line paid off.
It was Everton this time who failed to clear and after a bit of pinball in the area Villa's Norwegian kingpin fired home.
It gave the home side renewed hope and the fans didn't want half time to come. Carew had a penalty shout turned down and a succession of corners failed to pay dividends before referee Howard Webb blew his whistle for half time.
The start of the second half seemed to mirror that of the first.
O'Neill and Barry had clearly fired the team up in the dressing room as they emerged with yet more desire.
Unfortunately those defensive frailties were again exposed as South African maestro Pienaar turned his man and lashed in from the edge of the area.
Every man woman and child in the stadium must have thought it was game over.
Surely a side lacking in confidence, ideas and defensive stability couldn't salvage anything from this match. But, much to everyone's surprise, Villa conjured up some of that early season fighting spirit.
Boot
After Barry had been pulled down by Cahill, Milner curled in a superb free-kick from 20 yards.
The pendulum had now swung back in favour of the Claret and Blue and after a wave of attacks they finally restored parity.
Petrov surged into the area, only to meet the boot of Joleon Lescott who swung wildly in the face of the Bulgarian.
Webb, who was about as much of a fans favourite as Lescott himself, felt obliged to give the penalty after turning down two well founded earlier appeals.
Cometh the hour cometh the man and Barry underlined his importance to Villa with an emphatic spot kick which sent the Holte End into raptures. The midfielder had carried his side forward since the break with some tidy and tenacious play in the centre of the park.
Surely he cannot leave at the end of the season should Villa now, as expected, miss out on fourth place. What would the side do without him to pick up the pieces?
Villa had two great opportunities late on to seal what would have been an amazing victory but Nathan Delfouneso, on for the lifeless Gabby Agbonlahor, saw his shot saved by Tim Howard and Milner missed the target with a back post header.
A draw was probably a fair result but after getting back on level terms Villa probably feel they could have won the game.
Everton missed the opportunity to leapfrog their hosts into fifth but, in truth, they would not have even come away with a point had Knight and Davies defended properly.
For Villa it was a similar feeling of adulation to the one they experienced on Merseyside after an epic 3-2 win in December.
This result could prove crucial in the fight for fifth but unfortunately it may not be enough to keep the inspirational Barry at Villa Park next season.