Board-tans are anthropomorphic (or otherwise in some cases) personifications of boards on 4chan (and other chan based sites, but that's not what this page is for).
CreationEditBoard-tans were conceptualized when an image titled "4chan house" was posted on /r9k/ depicting the various boards living together in the same house doing things that were relevant to their board topics.
They did not gain noticeable popularity until after Three Angled Blue drew a comic depicting /b/'s failed 2008 invasion of /v/ where both boards were personified as characters. From there, some boards began developing their own personifications, while others had ones forced upon them if they didn't get around to doing it themselves.
Current boards with -tans: [ a / b / c / d / e / f / g / gif / h / hr / k / m / o / p / r / s / t / u / v / vg / vr / w / wg ] [ i / ic ] [ r9k ] [ s4s ] [ vip ] [ cm / hm / lgbt / y ] [ 3 / aco / adv / an / asp / biz / cgl / ck / co / diy / fa / fit / gd / hc / his / int / jp / lit / mlp / mu / n / news / out / po / pol / qst / sci / soc / sp / tg / toy / trv / tv / vp / wsg / wsr / x ] [ j / qa / trash ]