Mary McDonnell, who became a sci-fi darling on the acclaimed Syfy “Battlestar Galactica,” has found a second home  on cable TV on TNT’s “Major Crimes” as the steady, sturdy Capt. Sharon Raydor in L.A.’s Major Crimes division.

The two audiences may not overlap much, but both fan bases will gravitate toward her at the end of the month at Dragon*Con, the annual science fiction shindig in downtown Atlanta, where she’ll mingle with the masses and sign autographs to raise money for Sinta Gleska University, a Native-American college in South Dakota.

In a phone interview this week, she recalled her first trip to Atlanta for Dragon*Con in 2009 just as the drama was wrapping. “I was so grateful to the fans,” she said. “People who go to these conventions are often misunderstood. When I go to them, I’m just uplifted by the intelligence of the fans, the depth of the discussions, the connections they make. It’s like a football game that goes on for four days.”

McDonnell’s drama “Major Crimes” pulls in almost the same number of viewers as its powerhouse predecessor “The Closer” and is the most popular program on the Atlanta-based network. It just beats out “Rizzoli & Isles” with nearly 8 million viewers a week, counting DVR usage. Despite Kyra Sedgwick’s departure, a vast majority of “The Closer” cast stayed- as did most of the writing staff and executive producers.

McDonnell’s character isn’t showy or quirky the way Brenda Leigh Johnson was, but she brings a level of maturity and level-headedness to a heavily male office – minus the chocolate obsession, the over-sized purse and ridiculously unrealistic Southern accent.

Raydor’s original role breathing down Johnson’s neck over her questionable crime-fighting tactics in the Force Investigation Division is now a memory. “They used to call her Darth Raydor,” she said. “Every once in awhile we long for the days of Darth. Occasionally, she brings it back. But staying in that lane would have been too limiting.”

Raydor’s maternal side came out when she started housing a troubled gay teen Rusty two years ago after he became a key witness in an important long-running criminal case. She became attached to him and is now about ready to adopt him.

But last week’s episode revealed a fissure: her actual son Ricky shows up and is suspicious of Rusty, calling him a “con artist” who could take advantage of the family. She tells him she’s not asking for his permission to adopt Rusty. Her mind is set. But she is deeply disappointed in his narrow-mindedness.

Ricky, shocked by his mom’s feelings, relents and throws out a peace offering to Rusty.

McDonnell didn’t want to give away any spoilers about how the Rusty storyline will play out but said vaguely that “we’re moving into a different configuration of people with more complexity.”

While Brenda is living her life offscreen, her hubby and former FBI man Fritz (Jon Tenney) comes back on occasion to help on cases. TVLine says he may get his own spinoff of a spinoff. He appeared last Monday as well in a new role with the LAPD and left with a bit of a cliffhanger that hopefully Monday night’s summer finale will address.

Film lovers will also remember McDonnell for her role on “Dances With Wolves” 24 years ago. Her Lakota dialect coach introduced her to Sinte Gleska University on the Rosebud Reservation in South Dakota. She has been raising money for the school in recent years and plans to engage Dragon*Con fans to do the same.