I just wanted to note a couple of errors in the comments by raysond and add a couple of comments of my own.
Antonio Fargas was a guest star on Vega$ but never had a recurring role in the show. Bart Braverman played Dan Tanna's sidekick Binzer for the run of the show. Greg Morris played the proverbial police force contact for Tanna rather than his boss. Morris left the show after the second season and Naomi Steven's role was expanded to fulfill Tanna's need for somebody who could get the bad guy's records and deliver backup at just the right time. Tony Curtis, as Philip Roth, was as close as Dan Tanna had to a boss. Since Tanna lived on the premises of Roth's hotel, he had first dibs on his services but Dan was very much his own man.
Poster raysond also suggests that Robert Urich subsequently reprised the Dan Tanna role in the Spenser for Hire television series. Vega$ was actually a reprise of the Dan Tanna character which had first appeared in Charlie's Angels. However, the only commonality between Vega$ and Spenser for Hire was Urich's tough guy personality. Both shows had their own very unique styles, having to do as much with the values and lifestyle of the lead character as with their vastly different locales. Vega$ was the product of David Mann who would go on to greater fame as the creator of Miami Vice, another show that was known as much for its back drops as its actors and scripts.
Spenser for Hire was based upon the Boston private investigator in a series of novels by author Robert Parker (Parker continues to write Spenser novels although the character is getting a bit old in the tooth:)). As much as Vega$ and Miami Vice were dependent upon their backdrops: locales, clothing and vehicles; Spenser for Hire was dependent upon character and dialog. This was due in part to the ongoing participation of Robert Parker who is known for very well crafted dialog. The show was as much about Spenser's relationship with sidekick Hawk and love interests Susan and Rita as it was about the cases he handled. Urich played Spenser in four TV movies several years after the series ended.
Urich was a good actor who could be depended upon to deliver a credible performance in whatever role he took on. He will never be mentioned in the same breath with a Jack Nicholson or Clint Eastwood but his presence on the small screen has certainly been missed.
