Husband and wife team Howard Panter and Rosemary Squire, who run Ambassador Theatre Group (ATG), have topped the annual Stage 100 list, The Stage newspaper's compilation of the 100 most influential people in UK theatre, for the fifth year in a row.
The duo are close to equalling Andrew Lloyd Webber, who comes third this year, who has taken the crown six times.
Alistair Smith, deputy editor of The Stage and editor of The Stage 100, said: "In 2013, ATG was bought by private equity firm Providence in a deal worth in excess of £350 million. That deal was a game-changer and was the biggest theatre transaction that has ever taken place in the UK market. It was the theatrical equivalent of Roman Abramovich buying Chelsea in 2003."
A new addition to the top 20 is director Jamie Lloyd, who becomes the youngest director on the list since Sam Mendes (who this year is number 18 with Neal Street Productions partner Caro Newling) in 1998.
Other new entries to the top 20 include the Royal Shakespeare Company's Gregory Doran and Catherine Mallyon, producer Michael McCabe and Disney Theatrical Group's Thomas Schumacher.
Elsewhere in the full list, regional theatre is represented by people including Gemma Bodinetz, James Grieve and George Perrin, Paul Kerryson and Laurie Sansom, while performers include Michael Ball, Tamsin Greig, Adrian Lester and Sheridan Smith.
The full top 20 is as follows [last year's position]:
1= Howard Panter/Rosemary Squire (Ambassador Theatre Group) [1=]
2. Nicholas Hytner / Nick Starr (National Theatre) [1=]
3. Andrew Lloyd Webber (Really Useful Group) 
4 Cameron Mackintosh and Nick Allott (Cameron Mackintosh Ltd) 
5. Sonia Friedman (Sonia Friedman Productions) 
6. Michael Grandage / James Bierman (Michael Grandage Company) 
7. Bill Kenwright (Bill Kenwright Productions) 
8. Nica Burns / Max Weitzenhoffer (Nimax Theatres) 
9. Gregory Doran and Catherine Mallyon (Royal Shakespeare Company) [new entry]
10. Dominic Dromgoole and Neil Constable (Shakespeare's Globe) 
11. Daniel Evans and Dan Bates [Sheffield Theatres] 
12. Nick Thomas (Qdos Entertainment) 
13. Thomas Schumacher (Disney Theatrical Group) [new entry]
14. Scott Rudin (Producer) [new entry]
15. Jonathan Church and Alan Finch [Chichester Festival Theatre] (9)
16. David Lan (Young Vic Theatre) 
17. Josie Rourke and Kate Packenham (Donmar Warehouse) (17)
18. Sam Mendes and Caro Newling (Neal Street Productions) [new entry]
19. Michael McCabe (Producer) [new entry]
20. Jamie Lloyd (director) [new entry]
For the full 100 list, visit The Stage's website