(written from a Production point of view)
Merritt Butrick (3 September 1959 – 17 March 1989; age 29) was the American actor best known for his role as Dr. David Marcus in Star Trek II: The Wrath of Khan and Star Trek III: The Search for Spock. He later played T'Jon in the Star Trek: The Next Generation first season episode "Symbiosis". Footage of this character was later used in the second season episode "Shades of Gray".
Life and death
Butrick was born in Gainesville, Florida. He later moved to California, graduating from Tamalpais High School in Mill Valley in 1977. He studied acting at the California Institute of the Arts' School of Theater, but was told by his instructors that he did not have the skills needed to be an actor and was dismissed from the school. Butrick went on to receive steady work as an actor from 1980 through 1988.
By 1989, Butrick had developed AIDS. On 10 March, Butrick was suffering from toxoplasmosis of the brain and received a spinal tap/lumbar puncture to help relieve the cranial pressure. He was also suffering from pneumonia at the time. Butrick died in his Los Angeles apartment on 17 March at the age of 29 as a result of the various illnesses he developed due to AIDS. He was cremated and his ashes were given to his family in Lake Oswego, Oregon. He was the first known TNG guest actor to die.
There was some confusion as to where he died; reports exist which state that he was in New York City at the time,  but he was actually in his apartment on Hollywood Boulevard, close to where Roger C. Carmel died three years earlier. 
Butrick made his professional debut appearing as a rapist in two episodes of the police drama Hill Street Blues in 1981. James B. Sikking, Barbara Babcock, and Barbara Bosson were regulars on this series. Robert Butler, who previously directed the first Star Trek pilot, "The Cage", directed both of Butrick's episodes.
Butrick next appeared in NBC's 1981 TV movie Splendor in the Grass, along with Cyril O'Reilly, Graham Jarvis, and K Callan. He also made an appearance on CHiPs that same year, working with Gary Graham, Claudette Nevins, and series regular Robert Pine.
In 1982, Butrick was cast as New Wave music-loving high school student John Ulasewicz, aka "Johnny Slash", in the situation comedy series Square Pegs. This series aired for one season from September 1982 through March 1983 on CBS. Butrick then had a supporting role in the NBC TV movie When Your Lover Leaves, along with Dwight Schultz.
Butrick subsequently starred in the TV movies Sweet Revenge (with Alfre Woodard), Promises to Keep (with Randy Oglesby), Blood & Orchids (with George Coe, David Clennon, James Saito), Stagecoach (with Mary Crosby), and When the Bough Breaks (with David Huddleston). He also guest-starred on such series as Beauty and the Beast (working with Jeffrey Combs and series regular Ron Perlman) and Jake and the Fatman (with Bert Remsen).
Film and stage work
A month after Star Trek II was released in theaters, audiences saw Butrick in the popular teen comedy Zapped!, in which he played the supporting role of Gary Cooter. Other actors who appeared in this film include Ed Bakey, Carlos LaCamara, and Robert Mandan.
Following Star Trek III, Butrick had a supporting role in the 1985 comedy Head Office, along with Wallace Shawn. He then played the gang leader Reegus in the 1986 science fiction/action film Wired to Kill, which also featured Tommy "Tiny" Lister, Jr. Butrick followed this with roles in the films Shy People (1987) and Death Spa (1988), the latter of which co-starred Brenda Bakke.
His final film role was in the 1988 horror sequel Fright Night Part 2. His fellow cast members in this film included fellow Star Trek alum Brian Thompson.
In October 1988, Butrick portrayed an irritable but ditzy prostitute in the stage play Kingfish, which ran at the Los Angeles Theatre Center. His co-stars in this production were veteran Hollywood actor/writer/director Buck Henry and fellow Next Generation guest actor Sam Anderson. Time magazine praised Butrick's performance in Kingfish, calling it "a striking star turn of alternating vice and victimization".