1. Dr. Bogdanilivestsky 'Bob' Romansky on 'ER'

Pity poor Bob, the quiet emergency room receptionist seen on the first season of the medical drama. For starters, the doctors and nurses called her Bob because they couldn't be bothered to pronounce her Polish name, in Chicago no less. Then, as we learned in "Blizzard," as Bob slipped on rubber gloves to save a patient, she was a trained surgeon back in Poland. She merely did not have a license to practice in America. Carter offered to tutor her if she wanted to pursue it. Just as the character started to get interesting… she disappeared.

Image: Warner Bros. Television

2. Dr. Ben Samuels on 'St. Elsewhere'

Bob was not the first doctor to get ghosted on a television drama. A decade earlier, the same happened to Dr. Ben, played by David Birney, former husband of Meredith Baxter and star of Bridget Loves Bernie. The surgeon was a ladies man, and his romantic flings were constant plot points throughout the first season. Then, at the start of the second season, he was mysteriously absent… with no explanation.

Image: 20th Television

3. Athena on 'Battlestar Galactica'

Commander Adama's only daughter, played by former model and Cosmopolitan cover girl Maren Jensen, would seemingly be a key player in the saga of the Galactica. She was not only Adama's daughter and Apollo's sister, but a love interest to Starbuck. After the 17th episode, however, she is gone from the series. According to the website Chicago Now, Jensen clashed behind the scenes with the show's producer, who grew frustrated with her performances. What nobody knew at the time was Jensen reportedly had become afflicted with the Epstein-Barr virus, which led to chronic fatigue. 

4. Eugene Barkley on 'The Big Valley'

Yes, there was once another Barkley boy early on. Eugene, the youngest Barkley, appeared in a handful of episodes. Played by Charles Briles, Eugene was an excitable medical student studying at Berkeley. He popped up sporadically throughout the first season. Briles then received his draft notice from the Army. Producers wrote the character off the show, explaining he went off to med school. His name was mentioned just once again. Briles volunteered for the California National Guard and was on duty for the 1965 Watts riots, according to his obituary.

5. Jemima Boone on 'Daniel Boone'

After the second season, Jemima Boone, Daniel's daughter, vanishes from the series. The character was played by the great Veronica Cartwright, the sister of Lost in Space's Angela Cartwright. Why did she disappear? There was some behind-the-scene bickering. The producers hoped to introduce a love interest for the young Boone, played by teen idol Fabian. Blair, who played matriarch Rebecca Boone, was not a fan of the idea and gave a she-goes-or-I-go ultimatum. "The actress playing my mother didn't care for that, so she wouldn't sign her contract if they brought me back," Cartwright explained. "She felt that it aged her."

6. Kevin Hinkley on 'The Greatest American Hero'

Remember how Ralph, the Greatest American Hero, had a son? What did we learn about young Kevin? Well, he spotted his dad putting on a cape, he knows how to play chess, he watches The Lone Ranger reruns, and he likes trains. Then, after appearing in a handful of early episodes, Kevin goes bye-bye. It happened just as the writers changed Ralph Hinkley's name to Ralph Hanley, due to John Hinckley Jr.'s assassination attempt on Ronald Reagan. Hinkley was gone, as so was Kevin. Seems weird that the "Greatest American Hero" would forget his son.

7. Ethan Cragg on 'Murder, She Wrote'

Claude Akins, the former Sheriff Lobo of B.J. and the Bear and its spin-off, portrayed the crusty fishing boat owner who acts as a "Watson" to Jessica Fletcher. He was hardly a fan favorite, which might explain why the character vanishes without a trace. Or, of course, it could be more evidence to the wild fan theory that Jessica Fletcher was the real killer.

Image: The Everett Collection