Klitschko stands nearly a foot-and-half taller than his fiancee and, at 41, is 14 years her senior, with those aesthetic differences making them an eye-catching pair when they attend awards shows, sporting events and fashion events.
She has been ringside for a number of his fights, too, including his victory over Samuel Peter and the defeat by Fury which saw the Ukrainian head into the longest spell away from the ring of his career.
Panettiere was spotted without her engagement ring last summer, sparking rumours they had separated, but the actress was quick to put things straight.
Alongside a black and white photo of her with Wladimir and their daughter, she wrote: "Missing rings don't mean the end of relationships. Blessed to be with my beautiful family".
She is a regular on social media, occasionally featuring her partner and daughter in photos, including at the launch of the fight with Joshua in Times Square, New York City.
Alongside that image, she wrote: "I have his back, literally."
At 27, the New Yorker is a star of television and the big screen, a model and a Grammy-nominated singer, having seemingly been born into the entertainment industry as the daughter of a soap opera actress.
Indeed, she appeared on screen for the first time at the age of 11 months as she fronted a commercial for a toy train, before appearing in two different soap operas before her 10th birthday.
From there she had recurring roles in Ally McBeal, Malcolm in the Middle and Law & Order, but it was hit NBC show Heroes in which she really made her name as she played Claire Bennet, a high school cheerleader with regenerative healing powers.
On the big screen she has voiced characters in A Bug's Life and Scooby-Doo and appeared in Scream 4 in 2011, while she has also played her part in a number of video games.
More recently she has stared in musical drama series Nashville, releasing a number of tracks as a result, and played the title role in The Amanda Knox Story.
But this weekend all eyes will be on her partner, as he bids to make a successful return following his loss to Fury and prove experience is greater than youth by beating Joshua.
After defeat by Fury, Panettiere insisted her partner would always be a champion in her eyes, with the Ukrainian hoping to be able to be so in the eyes of the boxing world once again this weekend.