Use -notlike to filter out multiple strings in PowerShell

V2 at least contains the -username parameter that takes a string[], and supports globbing.

V1 you want to expand your test like so:

Get-EventLog Security | ?{$_.UserName -notlike "user1" -and $_.UserName -notlike "*user2"}

Or you could use "-notcontains" on the inline array but this would only work if you can do exact matching on the usernames.

... | ?{@("user1","user2") -notcontains $_.username}

I think Peter has the right idea. I would use a regular expression for this along with the -notmatch operator.

Get-EventLog Security | ?{$_.Username -notmatch '^user1$|^.*user$'}