London After Midnight (original working title: The Hypnotist) is a lost 1927 American silent mystery horror film directed and co-produced by Tod Browning and starring Lon Chaney, with Marceline Day, Conrad Nagel, Henry B. Walthall, and Polly Moran. The film was distributed by Metro-Goldwyn-Mayer, and was written by Waldemar Young, based on the story "The Hypnotist" which was written by Browning. Merritt B. Gerstad was the cinematographer, and the sets were designed by Cedric Gibbons and Arnold Gillespie. Harry Sharrock was the assistant director. The film cost $151,666.14 to produce, and grossed $1,004,000 (equivalent to $18,173,939 in 2024). Chaney's real-life make-up case can be seen in the last scene of the film sitting on a table, the only time it ever appeared in a film.

Browning remade the film as a talkie in 1935, as Mark of the Vampire, starring Bela Lugosi.

The last known copy of the film was destroyed in the 1965 MGM vault fire, making it one of the most sought-after lost silent films. In 2002, Turner Classic Movies aired a reconstructed version, produced by Rick Schmidlin, using the original script and numerous film stills to recreate the original plot.