I am pretty sure this is Green Spire Euonymus. I have it popping up in my garden too because my neighbor has a huge one. However, I kept a couple saplings and moved them to the border between our houses. That was about 3 years ago. I now have an attractive shrub with shiny green leaves and upright branches as the name implies. It keeps a narrow form and makes a good privacy screen.

Here is a video about it:
https://www.youtube.com/watch?v=9qwlRfbKCdw

Looks like Japanese Holly, Ilex Crenata 'Sky Pencil'. I thought that the slightly serrated leaves might be a clue.

I think that it's a Euonymus. It has opposite leaves, and hollies have alternate leaves.

Sorry Jimmy, don't know that Euonymus but pretty sure it isn't the Ilex. Mine has very much smaller leaves than that. Also the habit of the Ilex is much more compact.

Stera, I may not be correct but if you Google Ilex Crenata 'Sky Pencil' you will find that that this variety can grow up to 10 foot.

https://www.evergreennursery.com/euonymus-japonicus-microphyllus