Not quite perfect, but it got me closer than some of the top answers here.
Two different tables, one with the header, and the other, wrapped with a div with the content
<table>
<thead>
<tr><th>Stuff</th><th>Second Stuff</th></tr>
</thead>
</table>
<div style="height: 600px; overflow: auto;">
<table>
<tbody>
//Table
</tbody>
</table>
</div>