(written from a Production point of view)
Colla previously directed the unsold pilot for Gene Roddenberry's The Questor Tapes, which was written by Roddenberry and Gene L. Coon (earning them a 1975 Hugo Award nomination in the category Best Dramatic Presentation) and starred Robert Foxworth, Majel Barrett, and Walter Koenig. He went on to direct Star Trek: Deep Space Nine star Avery Brooks in five episodes of Spenser: For Hire and Brooks' DS9 co-star, Nana Visitor, in a 1985 episode of MacGyver. He also directed Diana Muldaur, Julie Newmar, and Gregory Sierra in a 1970 episode of McCloud. Other television series he directed include Gunsmoke, Ironside, CHiPs (again working with Julie Newmar), Murder, She Wrote (an episode with Samantha Eggar), and Hardcastle and McCormick (starring Brian Keith and Daniel Hugh Kelly in the title roles).
Colla directed TOS guest actors Steve Ihnat and Stewart Moss in two feature films: 1970's Zigzag and 1972's Fuzz. The former movie also featured William Marshall and Vic Perrin, while the latter featured Peter Brocco, Vince Howard, and Bert Remsen. Colla had previously directed Steve Ihnat in the 1969 TV movie The Whole World Is Watching (co-starring Kermit Murdock) and went on to direct Stewart Moss in the pilot for Sarge (1971, starring Ricardo Montalban), the unsold TV pilot The Tribe (1974, also featuring Meg Wyllie), and the ABC Movie of the Week Live Again, Die Again (1974, co-starring Walker Edmiston).
While Colla has always remained predominently a director for television, he inadvertently added an additional theatrical feature credit to the two he already had. He directed the two 1978 pilot episodes of the classic science fiction series Battlestar Galactica (featuring John Colicos and Ed Begley, Jr.), which were re-edited into a theatrical feature, premiering in the spring before the series actually started its televsion run in mid-September, thereby becoming the de facto start of the Battlestar Galactica franchise.
Among Colla's many other TV movie credits are 1971's The Priest Killer (co-starring Peter Brocco, David Huddleston, Kermit Murdock, and Anthony Zerbe), 1975's The UFO Incident (also with David Huddleston), 1986's That Secret Sunday (starring Daphne Ashbrook and William Lucking), 1989's Naked Lie (also with Lucking, as well as Dakin Matthews) and Blind Witness (starring Stephen Macht), 1990's Sparks: The Price of Passion (starring William Lucking), 1993's Desperate Rescue: The Cathy Mahone Story (starring Clancy Brown and Jeff Kober), 1994's Web of Deception (starring Rosalind Chao), and 1995's Zoya (featuring David Warner) and Dazzle (featuring Natalia Nogulich). His most recent project was the TV movie Growing Up Brady, starring Daniel Hugh Kelly (Star Trek: Insurrection).