(written from a Production point of view)
Julie Newmar (born 16 August 1933; age 86), birth name Julia Chalene Newmeyer, is a Los Angeles-born character actress who played Eleen in the Star Trek: The Original Series second season episode "Friday's Child". She filmed her scenes on Monday 22 May 1967 and between Wednesday 24 May 1967 and Monday 29 May 1967 at Desilu Stage 9, Stage 10 and on location at Vasquez Rocks Natural Area Park.
Newmar worked steadily from the early 1950s to the late 1980s, and less frequently thereafter. She is probably most famous for her role as Catwoman in the Batman television series, a role she accepted only after learning how enthusiastic her brother and his friends were about the show. She has appeared in various movies and specials about the show over the years since, and occasionally makes convention appearances. Other Trek alumni she appeared alongside in Batman are George Sawaya and Stanley Adams, while two episodes she appeared in were directed by Robert Sparr.
Prior to her Batman fame, Newmar played the titular character, a beautiful female android named "Rhoda" in the short-lived sitcom My Living Doll (1964-65). The character's codename, AF709 reportedly inspired the name of Seven of Nine on Star Trek: Voyager. 
Another of her better known science fiction appearances is as the War Witch Zarina on two 1980 episodes of the TV series Buck Rogers in the 25th Century, along with Tim O'Connor, Sid Haig, Michael Ansara, Felix Silla, and Kelley Miles. She also appeared as the Space Queen in two episodes of Jason of Star Command, with James Doohan and Sid Haig.
Newmar also appeared in various other television roles, including guest spots on series such as The Twilight Zone (with John Anderson and Guy Raymond), Route 66, Bewitched, Columbo (in an episode directed by Robert Butler), Fantasy Island (starring Ricardo Montalban), The Bionic Woman (with William Windom), The Powers of Matthew Star (in an episode directed by Leonard Nimoy, featuring Jeff Corey and Rudy Solari), and Hart to Hart (1984, with Perry Lopez and John Staible).
Newmar worked less steadily in feature films over the years. One of her earliest roles is an uncredited appearance in the 1953 musical The Band Wagon, alongside Robert Gist. She also played minor roles in films such as Demetrius and the Gladiators (1954, with Jay Robinson, William Marshall, and Gil Perkins), Seven Brides for Seven Brothers (1954, with Ian Wolfe), King Creole (1958) and Li'l Abner (1959) with Leslie Parrish. In the 1980s she appeared in a number of B-movies such as Nudity Required (1988), Deep Space (1988, with Michael Forest), and Cyber-C.H.I.C. (1989). She also appeared in the 1989 film Ghosts Can't Do It, and the 1994 science fiction movie, Oblivion, which was written by Peter David and co-starred George Takei, Carel Struycken, and Mike Genovese.
In 2003, she reunited with most of the surviving Batman cast members, including fellow Catwoman Lee Meriwether and Riddler Frank Gorshin, in the TV special Return to the Batcave: The Misadventures of Adam and Burt. Jason Marsden and Julia Rose played Burt Ward and Newmar, respectively, in 1960s scenes. Jim Jansen, Ray Buktenica, Steve Vinovich, Joel Swetow, Christopher Darga, and Todd Merrill also had roles in the special.
Newmar returned to the role of Catwoman in the 2016 animated film Batman: Return of the Caped Crusaders. This was followed in 2017 with Batman vs. Two-Face, which reunited her with William Shatner and the other Catwoman actress Lee Meriwether.
Julie Newmar has come to represent a beautiful but campy aesthetic of the 1960s, as celebrated in the 1995 film To Wong Foo, Thanks for Everything! Julie Newmar.