Is it possible to cross out cells in an HTML table?

Well, this is a bit hacky, but it works. Utilize linear-gradient

Using background-image for the current cell, strike through under content

table
{
  min-width: 100%;
}

table td
{
  border: 1px solid silver;
  position: relative;
}

table td.crossed
{
   background-image: linear-gradient(to bottom right,  transparent calc(50% - 1px), red, transparent calc(50% + 1px)); 
}
<table>
  <tbody>
    <tr>
      <td>Content</td>
      <td>Content</td>
      <td>Content</td>
    </tr>
     <tr>
      <td>Content</td>
      <td class="crossed">Content</td>
      <td>Content</td>
    </tr>
  </tbody>
</table>

Strike through table cell content using pseudo-element

If you want the strike through the content of the cell, you may also use pseudo elements, like this:

table
{
  min-width: 100%;
}

table td
{
  border: 1px solid silver;
  position: relative;
}

table td.crossed::after
{
  position: absolute;
  content: "";
  left:0;
  right:0;
  top:0;
  bottom:0;
   background-image: linear-gradient(to bottom right,  transparent calc(50% - 1px), red, transparent calc(50% + 1px)); 
}
<table>
  <tbody>
    <tr>
      <td>Content</td>
      <td>Content</td>
      <td>Content</td>
    </tr>
     <tr>
      <td>Content</td>
      <td class="crossed">Content</td>
      <td>Content</td>
    </tr>
  </tbody>
</table>