Witches' butter (or Witch's butter) may refer to:
Exidia nigricans, a black, gelatinous fungus Exidia glandulosa, a black, gelatinous fungus Fuligo septica, a yellow, gelatinous slime mold Tremella mesenterica, a yellow, gelatinous fungus Dacrymyces, a jelly fungus often confused with Tremella Nostoc, a genus of gelatinous cyanobacteria