Ryan Reynolds has only just realised what Blake Lively’s real name actually is

Ryan Reynolds and Blake Lively may have been married for more than a decade, but it seems there are still some mysteries within the relationship – including, um, their own names.

Ryan, 47, and Blake, 36, tied the knot back in 2012, and have since gone on to have four kids together – the youngest being little Olin, who was born last year.

The couple regularly post about one another online, often trolling each other hilariously on social media.

Today, however, Ryan took a moment to be a little more serious as Blake launched her brand new hair care range.

She wrote on Instagram: "Ever since I was a kid, through adolescence, early adulthood, motherhood, work, personal life, whenever, wherever, the single most identifiable part about me has always been my personalit— no? Not my personality? Oh… My hair.

Blake has launched a new hair care line (Instagram/@blakebrownbeauty)

“It’s my longest companion in life. For 36 years and counting. And like any relationship, it’s healthiest when you take good care of each other. To love it well, I’ve found a system that has worked wonders for me, a hack of sorts through decades of working with the very best people in the industry, and silly amounts of trial and error.

“I spent 7 years (I know. It toggles between impressive and wtf took so long) obsessively developing every detail of my newest baby, @blakebrownbeauty.”

She added: “It was a beast to build. But I couldn’t be prouder of it what we created for you.

“Time to fly from the nest baby…”

Husband Ryan paid tribute to his wife as she debuted her new venture, gushing in his own post: "I'm obscenely proud of this woman. She's been working on @blakebrownbeauty for 7 years.

"The result is exactly what you'd expect of a hyper-obsessive, detail addicted, uncompromisingly quality control genius."

But just to make sure there wasn’t too much sincerity, he added jokingly that he’d only just learnt what her last name really is.

"Also, I just found out her last name is Brown,” Ryan said.

Naturally, it didn't take long for her husband to say something (Instagram/@vancityreynolds/Vogue)

When her parents Ernie Brown and Elaine Lively welcomed baby Blake in 1987, they named her Blake Ellender Brown.

However, after they got married, Ernie decided to go against tradition by changing his surname from Brown to Lively – Elaine's surname from her first marriage.

It’s only now that Blake has launched Blake Brown Beauty that the penny’s dropped for many of us – including Ryan, it seems.