Allen is an internal promotion, and has worked at Fonterra since he started as a graduate in 2008.
Mitchell Pham is leaving after six years.
Ken Sutherland led the Hawke’s Bay consumer-owned electricity networks company for 20 years.
Jonathan Ogg has made the move from CBRE.
The four new partners are Grace Rippingale, Alex Franks, Vivian Cheng and Sam Holden.
New chief financial officer is Vedant Desai.
John Brakenridge moves onto 'new challenges' after 27 years in the top job.
New Zealander Greg Schollum will be Deputy Controller and Auditor-General for a three-year term.
Paula Nicolaou will be based in the firm’s Ōtautahi Christchurch office.