Ron Glass, the veteran actor best remembered as Sgt. Ron Harris on "Barney Miller" and Shepherd Derrial Book on "Firefly," passed away today. He was 71.

No cause of death has been announced, but TMZ reports that Glass recently battled "various illnesses" and had been watched at home by a caretaker.

Born in Evansville, Indiana, in 1945, Glass graduated from Saint Francis Seminary and went on to study drama and literature at the University of Evansville. He began his acting career in the early 1970s with guest appearances on such television shows as "All in the Family," "Hawaii Five-O," "Sanford and Son" and "The Streets of San Francisco" before landing his breakout role in 1975 on "Barney Miller." Starring opposite Hal Linden and Abe Vigoda, Glass played Ron Harris, a detective who lived beyond is means was was more concerned with his appearance, and his writing aspirations, than with police work.

Following the end of "Barney Miller" in 1982, Glass was cast as Felix Unger on the short-lived "The New Odd Couple" before going on to roles on such series as "Amen," "Rhythm & Blues," "Mr. Rhodes" and "Teen Angel."

The voice of Randy Carmichael on Nickelodeon's animated "Rugrats," and later on "All Grown Up!" Glass is perhaps best known to modern television audiences as Shepherd Book from Joss Whedon's "Firefly," a soft-spoken pastor with a mysterious past and a high-priority status within the Alliance. He briefly reprised the role in the 2005 film "Serenity."

In more recent years, Glass co-starred in the 2010 comedy "Death at a Funeral," and guest-starred on such TV series as "Marvel's Agents of S.H.I.E.L.D.," "CSI: Crime Scene Investigation" and "Major Crimes."