List ended the first day with a one-shot lead after he defied his lack of links golf experience to match the course record of 63 at Gullane, while Fowler, Westwood and English veteran Robert Rock all opened with confident 64s.
Fowler, who lifted the coveted trophy the last time it was played at Gullane in 2015, gave himself a chance to break 60 when he reached seven under with his fifth birdie of the round at the 12th but, like most of the field, he found the inward stretch a tough prospect.
The world No 7 dropped a shot at 13 and parred in from there to stay at six under, two strokes better off than he was en route to winning three years ago, and he was happy with his hot start having birdied two, three and four before driving the green at the sixth and holing the putt for eagle.
“I knew it was out there to get a few in the first six to nine holes, but at the same time, you’ve still got to hit fairways, hit greens and make putts,” said Fowler.
“So it was nice to go out and execute early and would have been nice to get a few more on the back. The back was playing tougher coming in and could have presented some trouble but I feel like we did a good job of avoiding that.”
Fowler was the second player to hand in a 64 after Rock, 41, had claimed the early clubhouse lead with a bogey-free opener, which featured three birdies over the first four holes, and the pair were later joined by Scott Fernandez, Jens Dantorp and a resurgent Westwood.
The 45-year-old, who now lives in nearby Edinburgh, also kept a bogey off his card and made his birdies in pairs at the first and second, fifth and sixth before further gains at 13 and 14 lifted him into a share of second.
“There’s a sense that things are getting back to where I wanted to be,” said Westwood, who has not won on the European Tour since 2014. “I’m hitting the ball on flights I haven’t seen for a while but I’m hitting a lot of good putts on the greens.
“You know, just trying to make a good action, really, and work on my technique and I know if I get that, keep doing that, then I’m going to see better things and see improvement.”
The quintet on six under were surpassed late in the day by List, who enjoyed a sparkling run of four straight birdies on the front nine before adding four in another prolific five-hole stretch from the 11th.
Masters champion Patrick Reed went one better than List on the outward half as he reeled off five consecutive birdies from the second and another gain at nine capped a superb, outward 29.
But the feisty American was not able to add any red numbers after the turn, and he blotted his card with a messy six at the long 16th as he settled with a 65 along with Tyrrell Hatton and European Ryder Cup vice-captain Robert Karlsson.
Former Masters champion Danny Willett continued his recent return to form with a solid 66 which was matched by last week’s Irish Open winner Russell Knox and Ian Poulter, while Justin Rose was one stroke further off the pace.
The world No 3 also made four birdies in a row on the front nine and made seven in total, but he did litter his card with three bogeys to slip outside the top 25 on a day in which 96 players managed to break the par of 70 in benign conditions by links standards.
But one of them was not Phil Mickelson, who offset three birdies with as many dropped shots in a frustrating opening round for the 2013 winner, while defending champion Rafa Cabrera Bello was two over after following an early birdie at the second with three bogeys to leave him facing a tough task to make the weekend.