In 2011, Twitter hit 100 million active users. See who joined.

January

11
Joaquin Lopez-Dóriga @lopezdoriga1
28
James Cameron @JimCameron

February

3
Howard Stern @HowardStern
5
Matt Drudge @DRUDGE

March

1
Charlie Sheen @CharlieSheen
21
Robin Roberts @RobinRoberts
22
Cristina Aguilera @TheRealXtina
28
Bronx Zoo's Cobra @BronxZoosCobra
29
Amtrak Northeast Corridor @AmtrakNEC

April

14
Billy Crystal @BillyCrystal
14
Nelson Mandela @NelsonMandela

May

9
U.S. Secret Service @SecretService
10
Jacob G. Zuma @SAPresident
25
Roberto Gomez Bolanos @ChespiritoRGB
27
Alec Baldwin @AlecBaldwin

June

1
Gwyneth Paltrow @GwynethPaltrow
1
Hope Solo @HopeSolo
5
Plaxico Burress @plaxico
9
Jill Abramson @JillAbramson
24
Dr. Willy Mutunga @WMutunga
29
The Pope @news_va_en

July

15
Jerry Seinfeld @JerrySeinfeld
16
Abby Wambach @AbbyWambach
19
Pharrell Williams @Pharrell
27
Mia Hamm @MiaHamm
29
Rafael Correa @MashiRafael
29
Rafael Nadal @RafaelNadal
29
Lewis Black @TheLewisBlack

August

30
Cheryl Cole @CherylCole

September

14
Jang Geun Suk @AsiaPrince_JKS
14
Salman Rushdie @SalmanRushdie
14
Juan Gabriel @1esJuanGabriel
16
Alan Partridge @ThisisPartridge
21
Melinda Gates @melindagates
29
House of Lords @UKHouseofLords
30
Ricky Gervais @rickygervais

October

3
Sean Parker @sparker
9
Gary Barlow @GBarlowOfficial
11
Samuel L. Jackson @SamuelLJackson
12
Condoleezza Rice @CondoleezzaRice
12
Eva Mendes @evamendes

November

16
Simon Cowell @SimonCowell