Which HTML5 tag should I use to mark up an author’s name?

For example of a blog-post or article.

<article>
<h1>header<h1>
<time>09-02-2011</time>
<author>John</author>
My article....
</article>

The author tag doesn't exist though... So what is the commonly used HTML5 tag for authors? Thanks.

(If there isn't, shouldn't there be one?)

Both rel="author" and <address> are designed for this exact purpose. Both are supported in HTML5. The spec tells us that rel="author" can be used on <link> <a>, and <area> elements. Google also recommends its usage. Combining use of <address> and rel="author" seems optimal. HTML5 best affords wrapping <article> headlines and bylines info in a <header> like so:

<article>
    <header>
        <h1 class="headline">Headline</h1>
        <div class="byline">
            <address class="author">By <a rel="author" href="/author/john-doe">John Doe</a></address> 
            on <time pubdate datetime="2011-08-28" title="August 28th, 2011">8/28/11</time>
        </div>
    </header>

    <div class="article-content">
    ...
    </div>
</article>

• The pubdate attribute indicates that that is the published date.

• The title attributes are optional flyovers.

• The byline info can alternatively be wrapped in a <footer> within an <article>

If you want to add the hcard microformat, then I would do so like this:

<article>
    <header>
        <h1 class="headline">Headline</h1>
        <div class="byline vcard">
            <address class="author">By <a rel="author" class="url fn n" href="/author/john-doe">John Doe</a></address> 
            on <time pubdate datetime="2011-08-28" title="August 28th, 2011">on 8/28/11</time>
        </div>
    </header>

    <div class="article-content">
    ...
    </div>
</article>

HTML5 has an author link type:

<a href="http://johnsplace.com" rel="author">John</a>

The weakness here is that it needs to be on some sort of link, but if you have that there's a long discussion of alternatives here. If you don't have a link, then just use a class attribute, that's what it's for:

<span class="author">John</span>

According to the HTML5 spec, you probably want address.

The address element represents the contact information for its nearest article or body element ancestor.

The spec further references address in respect to authors here

Under 4.4.4

Author information associated with an article element (q.v. the address element) does not apply to nested article elements.

Under 4.4.9

Contact information for the author or editor of a section belongs in an address element, possibly itself inside a footer.

All of which makes it seems that address is the best tag for this info.

That said, you could also give your address a rel or class of author.

<address class="author">Jason Gennaro</address>

Read more: http://dev.w3.org/html5/spec/sections.html#the-address-element

In HTML5 we can use some semantic labels that help organize the information regarding your type of content, but additional and related to the subject you can check schema.org. It is an initiative of Google, Bing and Yahoo that aims to help search engines to better understand websites through microdata attributes. Your post could look like this:

<article itemscope itemtype="http://schema.org/Article">
<header>
  <h1 itemprop="headline">header</h1>
  <time itemprop="dateCreated datePublished">09-02-2011</time>
  <div itemprop="author publisher" itemscope itemtype="http://schema.org/Organization">
    <p>
        <img itemprop="image logo" src="..."/>
        <span itemprop="name">John</span>
    </p>
  </div>
</header>
<section itemprop="articleBody" >
    My article....
    <img itemprop="image" src="..."/>
</section>
</article>