Gaga. Ooh la la! 'Bad Romance' catapulted Lady Gaga to the tallest point of pop. It was her grandest production, best vocal performance and catchiest banger until that point, and came with a scandalously good video that gave us iconic looks, an iconic murder and introduced the monster paw. What a time to be alive.
Kesha - 'Tik Tok'
How has it been ten years of Kesha? The party girl with a dollar sign in her name burst into our lives with this massive electro-pop anthem that name-dropped Diddy, make whiskey cool again and got the world dancing.
Miley Cyrus - 'Party In The USA'
'Party In The USA' is a special song that has stayed with everybody and has essentially became the soundtrack for America. The song itself is so massive even now that it's easy to forget what a moment it was at the time but this was really when Miley Cyrus, not the Hannah Montana girl, arrived.
Jay Z, Rihanna & Kanye - 'Run This Town'
After months of silence, Rihanna returned to the spotlight with a collaboration of epic proportions. Her second track with mentor Jay-Z and first with Kanye West, 'Run This Town' was a gritty, lighters-in-the-air anthem that still stands up well today.
Flo Rida & Ke$ha - 'Right Round'
Prior to 'Tik Tok', Ke$ha - sorry, Kesha - was already everywhere at the beginning of 2009 on Flo Rida's Number 1 single 'Right Round'. The only thing was she wasn't credited and didn't appear in the video so we had no idea we'd already been singing along to her for a long time.
Cheryl - 'Fight For This Love'
Here she is! Girls Aloud star Cheryl stepped onstage alone for her solo debut and everybody loved it. The nation's sweetheart responded to rumours of her then-husband Ashley Cole's infidelity with a punchy pop banger that defended their marriage in one super optimistic melody. With a military-themed video and debut performance, and ridiculous slitted trousers, it is truly a debut to remember.
David Guetta & Kelly Rowland - 'When Love Takes Over'
Let us just say something quickly: 'When Love Takes Over' is one of the best songs of all time. David Guetta leaped into the mainstream with this glorious, sunkissed, euphoric banger and brought Kelly Rowland back into our lives at the same time. Forever amazing.
Black Eyed Peas - 'I Gotta Feeling'
'When Love Takes Over' wasn't David Guetta's only big hit that year as he produced the Black Eyed Peas' third Number 1 single 'I Gotta Feeling'. Now a staple song to get your parents and aunties on the dancefloor at weddings, 30ths and so on, the low-key basic banger felt oddly revolutionary at the time.
Kelly Clarkson - 'My Life Would Suck Without You'
MY LIFE! WOULD SUCK! Kelly Clarkson chanted her way back into our lives with 'My Life Would Suck Without You', a 'Since U Been Gone' 2.0 stadium-ready pop banger that let us flex her insane vocal range and bring pop-rock back to the forefront. Bravo, KC.
Shakira - 'She Wolf'
Ah-ooooooh! Shakira is undoubtedly one of the most unpredictable artists we're lucky to have because some of her ideas are just so odd that only she could pull them off. 'She Wolf' is another prime example of this, as she made the seemingly bizarre concept into a disco-tinged floor-filler - and made the entire world howl in unison without questioning it.
Lily Allen - 'Not Fair'
A stomping rodeo-ready pop tune about an unsatisfactory sexual partner? Only Lily Allen could do it so well. The timeless classic is bloody hilarious but legitimately brilliant, and still goes off.
Jay-Z & Alicia Keys - 'Empire State of Mind'
We couldn't only have one Jay-Z song on this list when 'Empire State of Mind' exists. Now the unofficial anthem of New York City, Alicia Keys had everyone from Coventry to Aberdeen pretending they were in the Big Apple all year long.
Britney Spears - '3'
With the big comeback a huge success, Britney kept things moving while on the Circus Tour and dropped a greatest hits album to remind everyone yet again why she just is that bitch. (It's Britney, bitch.) A cheeky ode to threesomes, '3' was another massive hit for her and the second time in 2009 when she got away with singing so freely about sex on the radio. Legends only.
JLS - 'Beat Again'
Ah, JLS. The all-singing, all-dancing X Factor boy band who brainwashed the nation so much that people bought condoms with their logo on them. 'Beat Again' was the group's debut and it went right in at Number 1 on the charts, and it wasn't their last.
La Roux - 'Bulletproof'
La Roux quite frankly snapped on this karaoke classic. Good luck reaching those notes, though!
Pitbull – 'I Know You Want Me (Calle Ocho)'
The one and only Pitbull was just at the beginning of his reign in 2009 but that didn't stop him from dropping songs as huge as 'I Know You Want Me'.
Keri Hilson, Ne-Yo & Kanye West - 'Knock You Down'
#JusticeForKeriHilson: Even in the company of Kanye West and Ne-Yo (who were both at the top of their game when this dropped), Keri Hilson more than held her own on the dreamy single 'Knock You Down'.
Jason Derulo - 'Whatcha Say'
Kesha wasn't the only new kid on the block that year as Jason Derulo jumped into our lives with the Imogen Heap-sampling 'Whatcha Say' that stole our hearts.
Owl City - 'Fireflies'
Perhaps the most unlikely song to live on, Owl City's 'Fireflies' has become a strange cult classic among milennials. We're not complaining though - a bop is a bop. Thanks to Vine, we guess.