Ovid led the specification effort and did all the boring writing it up stuff because he wanted it to exist, Stevan Little (author of Moose) originated the idea but got distracted by real life before he got it finished, a bunch of us (including me quite a bit and even Damian Conway briefly) with a shitload of OO system design experience consulted and suggested and gave feedback.
LeoNerd (Paul Evans) I believe did a bunch of the code for both p3rl.org/Object::Pad (which was significantly an on-cpan prototype for this work) and the 'class' feature on his own time and also a bunch of it via sponsorship, though I'm less confident of the details there because since I can't write C to save my life I spent my tuits on the design and cat herding side and just assumed LeoNerd would get it right.
(the same approach worked out pretty well during the period he was doing dev work for me at https://shadow.cat/ too and we still keep an open contract with him in case we run into a LeoNerd-shaped problem, he is Just That Good IMO)
Perl continues to flourish into its fourth decade thanks to a vibrant community of users and developers. The following people are known to have contributed the improvements that became Perl 5.38.0:
Alex, Alexander Nikolov, Alex Davies, Andreas König, Andrew Fresh, Andrew Ruthven, Andy Lester, Aristotle Pagaltzis, Arne Johannessen, A. Sinan Unur, Bartosz Jarzyna, Bart Van Assche, Benjamin Smith, Bram, Branislav Zahradník, Brian Greenfield, Bruce Gray, Chad Granum, Chris 'BinGOs' Williams, chromatic, Clemens Wasser, Craig A. Berry, Dagfinn Ilmari Mannsåker, Dan Book, danielnachun, Dan Jacobson, Dan Kogai, David Cantrell, David Golden, David Mitchell, E. Choroba, Ed J, Ed Sabol, Elvin Aslanov, Eric Herman, Felipe Gasper, Ferenc Erki, Firas Khalil Khana, Florian Weimer, Graham Knop, Håkon Hægland, Harald Jörg, H.Merijn Brand, Hugo van der Sanden, James E Keenan, James Raspass, jkahrman, Joe McMahon, Johan Vromans, Jonathan Stowe, Jon Gentle, Karen Etheridge, Karl Williamson, Kenichi Ishigaki, Kenneth Ölwing, Kurt Fitzner, Leon Timmermans, Li Linjie, Loren Merritt, Lukas Mai, Marcel Telka, Mark Jason Dominus, Mark Shelor, Matthew Horsfall, Matthew O. Persico, Mattia Barbon, Max Maischein, Mohammad S Anwar, Nathan Mills, Neil Bowers, Nicholas Clark, Nicolas Mendoza, Nicolas R, Paul Evans, Paul Marquess, Peter John Acklam, Peter Levine, Philippe Bruhat (BooK), Reini Urban, Renee Baecker, Ricardo Signes, Richard Leach, Russ Allbery, Scott Baker, Sevan Janiyan, Sidney Markowitz, Sisyphus, Steve Hay, TAKAI Kousuke, Todd Rinaldo, Tomasz Konojacki, Tom Stellard, Tony Cook, Tsuyoshi Watanabe, Unicode Consortium, vsfos, Yves Orton, Zakariyya Mughal, Zefram, 小鸡.
