"The big boys" is a commonly used colloquial expression that refers to those who are powerful or influential in a particular industry or sector. However, there are several synonyms that can be used to replace this phrase. For instance, one could use the term "heavyweights" to refer to individuals or organizations that hold a dominant position in the industry. Another term that could be used instead of "the big boys" is "the top dogs," which also signifies a high-ranking position or influence. One could also use the term "movers and shakers" to refer to powerful or influential individuals who have the ability to affect change in the industry.