tasklist.exe

This shows all the running processes and the domain account they're running under (if applicable):

Show all running processes and account they're running under

tasklist /v

Search for just a specific process - like with "evil" in the title

This is handy if you've got a TGT-stealing exe running Rubeus for 60 seconds and you want to see if it is indeed running, but all you have is a PowerShell prompt and can't bring up anything in the gui:

tasklist | select-string -pattern "evil"