Woody's first appearance in "Knock Knock" is Deranged Animation. It does not help that when he first speaks, it is in a very normal tone compared to the later wacky tone he is known for.
The ending of "Pantry Panic": after Woody and the cat spent a good part of the short fighting over who would be dined by who, a moose happens upon Woody's door. They both rejoice at the sight ("Meat!" "Meat!") and the moose, terrified, runs away. Next shot is the moose's bones all piled up, with Woody and the cat next to them, having just finished to eat it... and the moose's dead head can be seen behind them.
Cat: "This was delicious, but you know... I'm still hungry."
Woody: (In an uncharacteristically even tone)"Yeah? So am I!"
[They draw their knives and get back to trying to kill each other.]
Barber of Seville, which is one of the 50 Greatest Cartoons, features Woody Woodpecker as a barber. The idea of this crazed nut with a razor is scary enough, but when he s l o w l y extends the razor as he glares into the eye of his current customer? Bring My Brown Pants.
The title card of the 1947 cartoon "The Coo Coo Bird" - the headshot of Woody from the side looks creepy.