Anonymous wrote:No one uses deputy in corporate. The second in command will be a person, not a title, and not all functions or departments will have the need for a second in command. There are many right-arms though. The go-to. The one whose opinion matters a little more than others. Again it is not designated by title. But the people will be known to those inside the company.
I assume OP is looking for resume help, so "right arm" is not really helpful.
OP, if you can do it in good faith, try Chief of Staff or Executive Officer. Otherwise you just have use the verbs in your resume bullets - you lead a team of managers, you are responsible for all decisions on this or that, etc.