sierramike

This widget allows you to display a JQuery responsive countdown timer on your website. You can use it as a widget or include it wherever shortcodes are supported.
It comes out of the box with french and german translations.
The widget contains media queries in its css stylesheet. You can edit it to suit your needs.
This widget also supports shortcodes!
Just add a [smcountdown timerdate=’xxx’] shortcode to any of you posts and you’ll get a responsive countdown timer! 
The shortcode supports one parameter: timerdate. 
* timerdate indicates the target date until which the timer counts down
Shortcode usage samples : 
[smcountdown timerdate=’2015/12/31 23:59:59′] 
Displays a countdown timer until Decembre 31th of 2015, 23h59m59s.

SM CountDown Widget

Displays a responsive JQuery countdown timer.

innovaxp

This plugin displays a countdown on a post.
Translation ready (i18n), now includes full translation to:
<ul>
<li>English (default).</li>
<li>Italian.</li>
</ul>
If you have a new translation for your language, please send us by email and we’ll add it to the package.

NS Countdown

This plugin displays a countdown on a post.

SM CountDown Widget vs NS Countdown