Rika (Sienna Guillory, left), Manny (Jose Pablo Cantillo) and Val (Gene Farber) hurry to help Commander Pike on the recent Virtuality two-hour pilot episode.

MCT

Star Trek was canceled after just three seasons, then grew into one of the most popular and influential franchises in science fiction history. Ever since, fans of the genre have pointed fingers, accusing TV networks of being too quick on the phaser with science fiction shows, canceling them without allowing time to build an audience.

True enough. But despite fans’ frustration at the loss of such series as Firefly and Terminator: The Sarah Connor Chronicles, this is a rich time for science fiction and fantasy on both network and cable TV.

Fox just aired Virtuality, Ronald D. Moore’s two-hour pilot for a proposed series, and BBC America has resurrected David Tennant’s Doctor Who.

Later this summer, Syfy (the renamed Sci Fi Channel) will introduce Warehouse 13, about FBI agents assigned to a top-secret warehouse housing mysterious artifacts, and bring back the wacky scientists of Eureka.

In the fall, new network offerings exploring global catastrophes, unexplained phenomena, vampires, witches and past-life regression will join the returning Dollhouse and Fringe on Fox, Chuck and Heroes on NBC, Supernatural on the CW and Lost on ABC.

Moore, whose popular and critically acclaimed Battlestar: Galactica ended its run this season, said that though the network ultimately passed on Virtuality, “I think if enough people watched and enough people got excited about it, anything is possible.

“Many of the most successful shows on TV had rocky starts,” he said, “and they really required networks that believed in the process and were willing to stick by them. . . . Unfortunately, we’re in an atmosphere where everyone is really worried about what’s going to happen next week.”

Sci-fi fans couldn’t be blamed if they were reluctant to get excited about a project clinging so tenuously to life. But here’s a look at other new shows on the schedule that fit into the sci-fi and fantasy genre.

•Warehouse 13, 9 p.m. July 7 on cable channel Syfy: FBI agents Joanne Kelly and Eddie McClintock are put in charge of retrieving supernatural artifacts and returning them to a secret warehouse in a series with X-Files overtones.

•Torchwood: Children of Earth, 9 p.m. July 20 on BBC America: The five-episode Series 3 airs as a miniseries, five nights in a row.

•Being Human, July 25 on BBC America: A 20-something vampire, werewolf and ghost are roommates.

•Doctor Who, 9 p.m. July 26 on BBC America: Tennant’s last appearance as the Doctor. Matt Smith takes over the role next year.

For fall and beyond:

•Flash Forward: The whole world blacks out in a mysterious event that also produces flashes of the future. Fall on ABC.

•Vampire Diaries: A high school girl is fascinated by a new boy who’s actually a centuries-old vampire. Fall on the CW.

•Eastwick: A new spin on The Witches of Eastwick. Midseason on ABC.

•V: The 1980s alien miniseries is updated. Midseason on ABC.

•Day One: A limited-run series follows a group of survivors after a global catastrophe. Midseason on NBC.

•Past Life: A team investigates past lives to solve problems in present lives. Midseason on