I managed to get just over half-way and recall 58 of them before I ran out. I find it interesting which are omitted. I assume these tags are just fully removed from HTML5, although most of them continue to work just fine with the exception of <blink>.

- <blink>

- <marquee>

- <tt>

- <center>

- <frame>

- <frameset>

That said, it accepts both <object> and <embed>, which I found moderately surprising, since I thought that those were mostly only used for ActiveX and NPAPI plugins. Maybe the last major round of deprecations for HTML came just a tad too early to kill them off, or maybe there is more to them than that.

Some tags I feel are underrated in handwriting HTML that are still in the spec: <figure> and <figcaption>, good for semantically representing images with captions. <thead>/<tbody>/<tfoot>, semantically segments a table; In theory could be used by assistive technology, or possibly renderers that need to paginate HTML and want the table headers to repeat on each page (does any agent do this?). <picture> + <source>, pure-HTML method of having responsive images in an HTML page, can support a fallback for browsers that don't support it, too. On that note, the srcset and loading attributes of img are very useful too, srcset as an alternative to <picture>, ostencibly aimed at use cases where the different sources are identical aside from pixel density (vs <picture> which is meant to contain potentially more significantly different images for different responsive layouts.)

I wonder which things I missed. That would be a nice feature to add.

(I know I missed a few table elements because I just thought of colgroup while typing this.)