Owner Count

Hi stefan 
Sorry I can’t understand your question , I have already given a query to list entire office 365 groups with entire owners (Mangedby or Mangedbydetails )count
Or
If you want name of all owners of a group you try with vasil query
Or
If you want Find office 365 groups list by specific owner in tenant try following query

$Ownername = "AlexW"
$groups = Get-UnifiedGroup -ResultSize Unlimited |select displayname,ManagedByDetails
$i=0
$groupname = ''
Foreach($group in $groups)
{
    $Gname= $group |Where-Object {$group.ManagedByDetails -eq "$Ownername"} |select displayname
    If($Gname -ne $null)
    {
        $j =1
        $i = $j +$i
        If($groupname)
        {
          $groupname= $groupname+","+$Gname.displayname.ToString()

        }
        else
        {
          $groupname= $Gname.displayname.ToString()

        }

    }
}
Write-host "$($Ownername) was owner of $($i) Groups"
Write-host "$($Ownername) was owner of following Groups : $($groupname)" 

Or
If you want total number of owner in tenant try following query

$mboxs= get-mailbox -ResultSize Unlimited -RecipientTypeDetails UserMailbox
$L =0
Foreach($mbox in $mboxs)
{
    $groups = Get-UnifiedGroup -ResultSize Unlimited |select displayname,ManagedByDetails,@{N="Ownercount"; E={($_.ManagedByDetails.count)}}

    $i=0
    $groupname = ''
    Foreach($group in $groups)
    {
        $Gname= $group |Where-Object {$group.ManagedByDetails -eq $mbox.Identity} |select displayname
        If($Gname -ne $null)
        {
            $j =1
            $i = $j +$i
            If($groupname)
            {

            $groupname= $groupname+","+$Gname.displayname.ToString()

            }
            else
            {
            $groupname= $Gname.displayname.ToString()
            }

        }
    }
    

    if($i -ne 0)
    {
    $K=1
    $L = $L+$k
    Write-host "$($mbox.Identity) was owner of $($i) Groups"
    Write-host "$($mbox.Identity) was owner of following Groups :"  -NoNewline
    Write-host "$($groupname)" -ForegroundColor Red 
    Write-host "----------------------------------------------------------------" -ForegroundColor Green
    }

}
Write-Host "Total number of office 365 group owners in the tenant is $($L)" -ForegroundColor Yellow