as far as movies go, "Song of the sea", by Tomm Moore while not really spooky, is set at halloween and deals with the supernatural in what I'd call a comfy way.
And for TV series, the only not obvious (Over the garden wall and GF) one that comes to mind is "Pumpkin reports". a simple CG cartoon about a pumpkin based alien infiltrating earth as a little girl to prepare for the imminent invasion.
I only have the theme song athand but I remember someone having a MEGA https://youtu.be/0uxx5vkTch0
But maybe I can help more with shorts:
young grim reapers grow up:https://youtu.be/Mptpw8fQ-lw
Spooky cartoon pilotshttps://youtu.be/0l940bPkV1ohttps://youtu.be/YcchrgJgryo
a small story about a goth girl trying to summona demonhttps://youtu.be/fxdvZR1ncmA
Mentally unstable child goes to hell... and back!https://youtu.be/5LQe5nR2CgM
An old newgrounds series abou a sentient zombiehttps://youtu.be/J70azufCPOc
... that's apparently getting a continuation!https://youtu.be/HEtwE7CpKK8
And, may I suggest to play also Villains songs? they usually are about pretty gruesome things, and the villains always have the best songs.https://youtu.be/vpLRJyWe814
and that's it. I hope something I posted was actually helpful.
But maybe I can help a little more suggesting shorts: