- Title: Uncanny X-Men
- Issue: #221
- Volume: #1
- Publisher Marvel Comics
- Date: September 10, 1987
- Written By: Chris Claremont
- Pencils: Marc Silvestri
- Inks: Dan Green
- Colors: Glynis Oliver
- Letterer: Tom Orzechowski
- Cover by: Marc Silvestri
- Key Issue: First appearance of Mister Sinister.
here is a nice key issue. the first appearance of Mr. Sinister.