Does anyone know if it's possible to freeze row headers in a report?

if you mean to show only summary level - yes, it can be done in customizing your report where on Edit Layout tab you select Display as Cannot Expand (only applies to financial reports)

Technically, all NetSuite reports have the header frozen in the UI... but let us know if that's not what you're asking.

I'm not sure how I missed these responses, but what I mean is not having the row names/GL accounts run off the page when we scroll to the right on a report. Similar to freezing rows or columns in Excel

Ah, I see what you're saying. Unfortunately, I don't believe that's possible.