what was the last film Bela Lugosi ever appeared in?

Answer 1

Was it not Plan Nine From Outer Space... and he died halfway through it?

Answer 2

"Late in his life, he again received star billing in movies when filmmaker Edward D. Wood, Jr., a fan of Lugosi, found him living in obscurity and near-poverty and offered him roles in his films, such as Glen or Glenda (in which his role made no more sense than the rest of the movie) and as a Dr. Frankenstein-like mad scientist in Bride of the Monster. During post-production of the latter, Lugosi entered treatment for his addiction, and the premier of the film was ostensibly intended to help pay for his treatment expenses. The extras on an early DVD release of Plan 9 from Outer Space include an impromptu interview with Lugosi upon his exit from the treatment center, which provide some rare personal insights into the man. During the interview, Lugosi states that he is about to go to work on a new Ed Wood film, "The Ghoul Goes West". This was one of several projects mooted by Wood, including "The Phantom Ghoul" and "Dr. Acula." With Lugosi in his famed Dracula cape, Wood shot improptu test footage in a suburban graveyard. This footage ended up in Plan 9 from Outer Space.
Following his treatment, Lugosi made one final film, in late 1955, The Black Sleep, for Bel-Air Pictures, which was released in the summer of 1956 through United Artists with a promotional campaign that included several personal appearances. To his disappointment, however, his role in this film was of a mute, with no dialogue."