1. Britney Spears
An entire episode was dedicated to the Princess of Pop, with the Glee cast trying their hand at covering some of Britney’s biggest hits. The singer made an appearance throughout, as the object of some rather fanciful Britney-themed hallucinations.
2. Gwyneth Paltrow
Gwynnie, she of the yoga lifestyle and macrobiotic diets, gave a surprisingly hilarious performance as kooky substitute teacher Holly Holiday. Gwyneth also proved that she has some vocals to reckon with, as she sung covers of hits such as Cee-Lo Green’s “Forget You” and Fleetwood Mac’s “Landslide”.
3. Lindsay Lohan and Perez Hilton
LiLo and Perez teamed up to play satirical versions of themselves, hired as celebrity judges for the glee club nationals. The two are at their best bitching and sniping away at each other - which is what we thought they did in real life anyway.
4. Ricky Martin
If Ricky Martin had been our Spanish teacher, we’d probably have paid more attention in class. Especially if he broke into impromptu performances of “Sexy and I Know It”, as he did in a Season 3 episode of Glee. Who knows, we might even have learnt some Spanish.
5. Josh Groban
The American singer-songwriter is best known for his power ballads and Grammy nominations, but on Glee Josh revealed himself to have a preference for “blousy alcoholics” – whilst referring to himself in the third person.