Brother to the Doorman, he's every bit as chicken - hiding behind windows where he thinks he's safe. Grab his grenades and sling 'em back! - Official description from the manual

The Windowman of Doom is an enemy in Battletoads & Double Dragon. The Windowmen appear throughout Stage 5, where they employ a tactic similar to the Doorman of Doom from Stage 2, throwing dynamite at the player while hiding safely behind windows. Unlike the Doorman, who requires multiple sticks of dynamite in order to be defeated, the Windowmen can be defeated with just one dynamite each.