In addition to the regular monthly Events Calendar, I have now started a separate Halloween Calendar for your perusal.
The calendar features all the great things happening on October 31st, but also ongoing events that span all of October like Sea World's Howl-o-Scream. Also included are one-time Halloween-themed events that happen on days other than October 31 but are still just as spooky and fun!
The Halloween Events Calendar is a part of the larger Halloween in San Antonio feature that also includes costume shops and ghost tours. Check it out, and look back often for changes and additions.