Meetups
Meetups are casual, regular gatherings where you can ask questions of your peers, and very likely, make a presentation yourself.
Macbrained
Macbrained MSP
MacAdmin Monthly
Seattle Mac Admins
London Apple Admins
Austin Apple Admins
Dallas Apple Admins
Houston Apple Admins
Macbrained YVR
MacDMV (Washington, DC)
Atlanta Apple Admins
Greater Philadelphia Mac Admins
East Midlands Apple Admins
Mac Admin and Developer Conference UK (MacADUK) - London, England
MacDevOps:YVR - Vancouver, Canada
MacDeploy - Calgary, Canada
Penn State MacAdmins - Penn State College, PA, USA
X-World - Sydney, Australia
MacSysAdmin - Gothenburg, Sweden
MacTech Conference - Los Angeles, CA, USA
MacTech Pro - Various cities and dates across the US
Objective By The Sea - Twice a year Apple-focused security conference in Hawaii and Europe
JAMF Nation User Conference - Minneapolis, Minnesota, USA
MacAdminsUA - Kyiv, Ukraine
ACEs Conference - Annual, various locations - check the site for info
MacAdmins Slack
MacEnterprise Mailing List
Apple Mailing Lists
Apple Discussions
JAMFNation
Munki User Mailing List
AutoPkg (command line tool) Mailing List
AutoPkgr (GUI app) Mailing List
Microsoft Office for Mac Resources