There is no single title used by every Protestant church. “Pastor” and “minister” are the most common broad terms, while “Reverend” is a style of address. Depending on denomination, a Protestant leader may also be called elder, bishop, priest, preacher, rector, or another title.

Pastor and minister
Pastor emphasizes the role of caring for and leading a congregation. Minister is broader and can refer to an ordained person authorized to preach, teach, administer rites, or serve a church.
Many Baptist, evangelical, Pentecostal, Lutheran, Reformed, Methodist, and nondenominational communities use one or both terms.
Is Reverend a job title?
“The Reverend” is traditionally a form of address rather than the name of an office. A person might be “the Reverend Jane Smith” while serving as pastor of a congregation.
Everyday usage is looser, so people sometimes say “our reverend,” but denominational style guides may distinguish title from office.
Elders and bishops
Presbyterian and Reformed traditions often use elder, though teaching elders and ruling elders can have different roles. Methodist, Anglican, Lutheran, Pentecostal, and other churches may use bishop, but the authority attached to that office varies greatly.
Some Protestant churches reject episcopal hierarchy entirely.
What about priest?
Anglican and some Lutheran traditions use the title priest. Many other Protestants avoid it because they emphasize the priesthood of all believers or use different understandings of ordained ministry.
The word therefore cannot be used as a universal synonym for Protestant pastor.
Best practical answer
If you do not know the denomination, pastor or minister is usually safest. When speaking to a specific congregation, use the title that community uses for its own leader.