SharePoint Online: Get Site Owner using PowerShell

Requirement: Get SharePoint Online Site Owner using PowerShell

How to Identify Site Owner in SharePoint Online?
You can find site owner SharePoint Online from SharePoint Online Admin Center.

• Sign in to SharePoint Online Admin Center (https://YourDomain-admin.sharepoint.com/_layouts/15/online/SiteCollections.aspx)
• Select the site collection you wish to get site owner from the site collections list >> From the ribbon, Click on "Owners" and then "Manage Administrators. 
• On the "Manage Administrators" dialog box, You'll get the site owner or primary site collection administrator.
  

PowerShell to Get Site Owner in SharePoint Online:
Here is the SharePoint Online PowerShell to list site owners

#Variables for Admin Center & Site Collection URL
$AdminCenterURL = "https://crescenttech-admin.sharepoint.com/"
$SiteURL = "https://crescenttech.sharepoint.com/sites/marketing"

#Connect to SharePoint Online
Connect-SPOService -url $AdminCenterURL -Credential (Get-Credential)

#sharepoint online powershell get site owner
Get-SPOSite $SiteURL | Select Owner

Get Site Owner in SharePoint Online using PowerShell
Here is how to get site owners of all SharePoint Online sites.

$AdminCenterURL = "https://crescenttech-admin.sharepoint.com/"

#Connect to SharePoint Online
Connect-SPOService -url $AdminCenterURL -Credential (Get-Credential)

#Get Site owners of all site collections
Get-SPOSite -limit ALL | Select URL, Owner

and the result:

The site owner is automatically added as Site collection administrator of the site. If you want to get all site collection administrators, use: SharePoint Online: Get Site Collection Administrators using PowerShell