Final answer:
John McCain is the Arizona Senator who gained his seat in 1986, succeeding Barry Goldwater, a leading conservative figure of the time.
Step-by-step explanation:
The Arizona Senator who gained his seat in 1986 is John McCain. McCain succeeded conservative Senator Barry Goldwater, who was a significant figure in the conservative movement and the Republican nominee for president in 1964. Goldwater was known for his opposition to the 1964 Civil Rights Act and his belief in a limited federal government.
However, despite his personal claim to support the goals of integration, his political stance distanced him from many voters. John McCain, on the other hand, became a prominent Republican leader and like Goldwater, he too secured the Republican nomination for president but was unsuccessful in the general election, losing to a Democratic candidate.