Marty's gang dominates a wide range of criminal activities in Vice City's poorer communities, such as loan sharking, prostitution and protection racket. Victor Vance works for Marty, after Phil Cassidy, Marty's brother-in-law told Vic about him. Marty was married with Phil's sister, Louise Cassidy-Williams and he was father of Mary-Beth Williams. He is shouted at her, he is abuses his wife if wants to deserve it. Marty is a stereotypical redneck - and he likes alchool. One day, Marty was very angry and shouted Louise, because the baby was cried. Louise went to her sister's house and Vic helped her.
In the mission D.I.V.O.R.C.E, Marty kidnaps Louise and Vic chase him. Marty stops in his brothel but Victor kill him.
 Mission appearances
GTA Vice City Stories
- Fear the Repo
- Waking Up the Neighbors
- O, Brothel Where Art Thou?
- No Protection?
- D.I.V.O.R.C.E (Killed)
Name: Marty Jay Williams
Nationality: Template:Flagicon American
Place of Birth: Vice City
Year of Death: 1984
Home: Viceport, Vice City
- Phil Cassidy (Brother-in-law)
- Louise Cassidy-Williams (ex-wife)
- Mary Beth Williams (daughter)
- Umberto Robina (formely friend)
- Victor Vance (formely friend)
- Mary- Jo Cassidy (Sister-in-law)
*Prostitution *Loan Shark *Protection Racket
Voiced by: Jim Burke