McGillion will reprise his role of Dr. Carson Beckett in the show’s fourth season, even though his character was unexpectedly killed in an explosion at the end of Season 3.

In addition to McGillion’s return, "Atlantis" viewers can also look forward to guest appearances by Torri Higginson, who played Dr. Elizabeth Weir on the show until last season's catastrophic season ender, and Christopher Judge who played Teal’c on "Stargate SG-1."

Judge’s fellow "SG-1" cast-mate, Amanda Tapping, will also move to "Atlantis," reprising her character, astrophysicist Col. Samantha Carter.

Jewel Staite, who played lovable Kaylee on the now-defunct sci-fi series, "Firefly," will also join the show.

The new season is slated to begin Sept. 28.