The Huntress' closest ally was her step-brother, Dick Grayson aka Robin.  Though more than twenty years separates them in age, Robin treats his "little sister" as an equal.  In fact, on one occasion when the Joker came out of retirement to bedevil Gotham, Robin disguised himself as Batman to lure the fiend out, but allowed the Huntress to apprehend him.  They had a brief romantic interest, but remained good friends.  Robin began his career as an attorney at "Cranston, Grayson and Wayne", and later become ambassador to South Africa.  He was a member of the All-Star Squadron and, in the 1960's, joined the Justice Society of America (which had been his life-long goal).

When the nephew of Sylvester Pemberton (aka the Star Spangled Kid) used the family fortune to create a high tech gang to plunder Gotham City (All-Star Comics #71), it was up to the Kid and Wildcat to apprehend them.  Unbeknownst to them, a new crime fighter was appearing on the scene, the Huntress!  Allied with her, they successfully defeated the gang, and, when the Kid realized that he should reclaim his family inheritance instead of playing superhero, the Huntress claimed his roster spot in the Justice Society of America. Since then, she has been a valued member of the JSA, gaining many valuable allies over time.

When a second generation of heroes attempted to gain membership and were denied into their predecessor's group, the Justice Society of America, they formed their own group...Infinity, Inc.  The Huntress and Power Girl joined this team as well, out of protest for their treatment.  They then battling (and defeated) their parents and guardians in the Justice Society, who were brainwashed toward evil by the Ultra-Humanite.  The Huntress and Power Girl returned to the Justice Society, while becoming an honorary members of Infinity, Inc.

The modern day Batman had a unique relationship with the Huntress, she being the daughter of his Earth-2 counterpart.  They frequently visited one another, and she often turned to her "Uncle Bruce" for advice...or just a shoulder to lean on, what with both of her parents having passed away.  On her first visit to Earth-1, she ended up facing Batman's foe the
Catwoman (before she reformed).  They later worked together to solve Mr. Terrific's murder, and saw one another in a few other annual meetings between their respective teams.  On another visit to Earth-1, it was Helena who provided support for Bruce, when feelings of despair over his parents' death resurfaced.  Strangely, Helena is his closest relative!