The figures show that men are paid nearly 65% more per hour at high street fashion store Phase Eight and nearly 52% more at EasyJet.
Organisations with 250 or more workers must publish their figures by April, and so far 527 firms have done so.
Nearly half of the organisations pay men at least one tenth more per hour and 426 of them pay men more, on average, per hour.
Thousands more firms, public sector bodies and other organisations are expected to reveal their gender pay gaps in the next few months.
EasyJet, which has been reporting on its pay gap since 2015, says the reason for the difference in hourly rate is because its best paid staff tend to be male pilots, while lower paid cabin crew are more often women.
A statement on its website says: “easyJet’s gender pay gap is strongly influenced by the salaries and gender make-up of its pilot community, which make up over a quarter of its UK employees.
“Pilots are predominantly male and their higher salaries, relative to other employees, significantly increases the average male pay at easyJet
“easyJet is seeking to encourage more women to become pilots through its Amy Johnson Initiative. It has set a target that 20% of new entrant pilots should be female by 2020.”
A statement on the Phase Eight website said: “The figures result from the fact that, as a women’s fashion retailer, the staff in our stores are overwhelmingly female, whilst our corporate head office staff (whose pay rates are typically higher) are more evenly split between men and women.
“We are confident that women and men are paid equally for doing the equivalent jobs across our business.”
Public sector bodies that show a wide divergence in pay per hour include the Royal Orthopaedic Hospital in Birmingham (men paid 34.8% more than women), and the Office for Nuclear Regulation (32.9%).
Many of the firms in the top 20 in terms of those with biggest gaps are in financial services, including Virgin Money (32.5%), PriceWaterhouseCoopers (33.1%) and asset management firm Octopus Capital (38.1%).
Virgin Money says on its website: “We are passionate about fairness, equality and inclusion and are committed to reducing our gender pay gap. We are confident that men and women are paid equally for doing equivalent jobs across our business.”
PriceWaterhouseCoopers said: “Our analysis of our gender pay gap shows that it is largely driven by the fact that there are more men in senior higher-paid roles within the business. We continue to take action to address any gaps and to make sure our policies and practices are fair.”
Two utility firms, which were part of the state sector until they were privatised in the 1980s and 1990s, are also in the top 20.
United Utilities pays men 36.7% more and Scottish Hydro Electric Transmission pays them an extra 33.4%.
United Utilities says: “We have a single pay and grading structure for all employees and use market-benchmarked rates for all roles. We have robust processes in place to ensure that pay is reviewed fairly for all employees.”
The full list can be found here.