In this article, we take a closer look at this year's shortlist, to see who will be joining this illustrious list of talent.
Who will you vote for? Head over to the voting page to have your say.
1. Anne-Marie Duff - Strange Interlude at the National, Lyttelton
With her husband (James McAvoy) also vying for an award in the Best Actor category, Duff may have to start thinking about clearing some space on the mantle piece. Especially after the Daily Telegraph said that she brought "a raw thrilling intensity to the stage" with her performance in Eugene O'Neill's audacious epic.
Do you agree? Vote for Anne-Marie Duff as your favourite here.
2. Hayley Atwell - The Pride at Trafalgar Studios
Atwell's performance in the revival of Alexi Kaye Campbell's play The Pride at the Trafalgar Studios was described as "Mesmerising" in Michael Coveney's review for WhatsOnStage.
If Hayley is your favourite for Best Actress then vote for her today!
3. Helen Mirren - The Audience at the Gielgud
Aside from her, now infamous, incident with drummers at the stage door, Mirren's second outing as Queen Elizabeth II, received rave reviews, the Daily Mail saying: "Dame Helen Mirren is now so good at playing the Queen, you could stick her on stamps and people would lick them."
If you think Dame Helen's performance is worthy of this award, head over to the voting page today and have your say.
4. Suranne Jones - Beautiful Thing at the Arts
Perhaps better known for her roles in Coronation Street and Scott & Bailey, Jones is actually a previous WhatsOnStage Award winner, winning the Best Supporting Actress award for her performance in A Few Good Men in 2005. Exuent Magazine said her performance in Beautiful Thing brought "spot-on comic timing and great lightness of touch to a complicated, nuanced character"
To vote for Suranne click here today!
5. Tanya Moodie - Fences at the Duchess
Moodie was heralded by critics for her performance in one of the American dramas of the 20th century. Libby Purves from The Times said "Tanya Moodie is a marvellous study in humour, sensuality and firm character."
If Tanya is your favourite for the Actress in a Play award, head on over to our voting page to cast your vote.
Who will get your vote? Voting is open until January 31st, make sure you don't miss out on your chance to have your say on the only major theatre awards voted for by the public.