I love Japanese culture, especially when it concerns anything ninja or samurai. I would really like to know what the actual creed/symbol is for the Hattori clan is, but Google images gives me a bunch of mixed messages, the main one being this:
The most consistent symbol I've seen in Google searches is the image posted, but I would like to be 100% certain.
What you're looking at here is the mon 紋 or 家紋 kamon. These area family crests (hence the ka part, which we can translate as Family) which do have some variability in how they're rendered, despite general themes.
Hattori Hanzo was a member of the Hattori 服部 family, not Hanzo. The surname is first. You've linked to a version of the Hattori mon.
That said, what you've pasted is basically okay, as it at least has the two darts/arrows^1 as the key element. See this 17th century portrait of Hattori, in which you can see the emblem on the clothes he's wearing, about where his knees would be.
Not that I assume you can read Japanese, but this page gives a similar design. The majority of the content on that page actually has to do with Hattori Hanzo (服部半蔵) as the well-known Hattori and the likely reason one would be looking up that particular kamon.
And hey we all like sources right? How about a primary source. Here's a photo of the gravestone of another Hattori, on which you can see quite clearly the crest.
So there you have it set in stone, and you don't have to worry about other mismatches you find on Google Images, unless of course they're just regular variation which as I mentioned is already to be expected.
Also by the way here's Hattori Hanzo's gravestone in case it got you wondering.
See also the fourth row down on this page (just below the swastika one) which is about Hanzo but includes the crest from another gravestone, or the couple other variants on stones here which for most are also Hattoris, except not the one with two crossing feathers^2.
Hope that helped!
That site is generally good but actually there seems to be a mistake on that specific page where they've shown a crest nearly identical to the one you've given but labeled it as belonging to the Minamoto (源) clan, but actually Minamoto had a very different and quite distinct kamon. It's kinda a huge mistake, so I'm surprised they haven't noticed.
… which is actually a motif used in a number of families' crests, and anyway they blurred out the surname in that photo so I wouldn't be able to tell you which it's representing in that case anyway. It's super common
Full disclosure: I'm not a historian of Japanese anything, other than Occupation-era language policies. I am however fairly obsessed with graveyards, and have spent a fair amount of time looking into these. I'll happily defer to any of our Japan experts should they show up point out any mistakes in the above post.
