RAMONA, Calif., July 5— Ross Martin, an actor who appeared in more than 200 film, stage and television productions and who was best known for his role in the television series ''The Wild Wild West,'' died Friday. He was 61 years old. Mr. Martin collapsed while playing tennis in 100-degree heat here. Mr. Martin portrayed Artemus Gordon, No. 2 spy in the CBS series that was set on the western frontier in the 1870's and featured two United States agents who used sophisticated mechanical devices.