"He was such a sweetheart," the actress, 59, told People.com. "I've known him since Nov. 28, 1972!"
The late actor, who was 60 when he died this week, first worked with Henner when both were hired as replacement cast members in the original Broadway production of 'Grease,' staged in the early '70s. Conaway played Danny Zuko at the time (the role immortalized by John Travolta in the hit film version, in which Conaway played Kenickie).
"We did 'Grease'together before we did 'Taxi.' We traveled in the national company of 'Grease' .. so I was connected to him, and worked with him quite a few times. We were like babies together. And then when he got 'Taxi' it was so great. He always reminded me of my brother Tommy, and I always reminded him of his sister Michelle, so we felt a real familial kind of connection."
Henner reportedly became choked up as she recalled Conaway as "the nicest person.... He was such a sweetheart, you know, a character. He had this wicked sense of humor, but he was so sweet, so sweet, in a way that I think a lot of people don't realize.... He was just a doll. Oh, we always talked on the holidays and stuff."
The actress told E! that she and her 'Taxi' co-star Tony Danza visited their ailing friend "almost daily" in the hospital where he ultimately took his last breath. She said in a statement, "Jeff looked the healthiest I'd seen him in a long time, and I really thought that he was going to come out of this."
Travolta recently spoke out about his friend's passing, saying, "Jeff Conaway was a wonderful and decent man, and we will miss him."