There are 13 members in Super Junior. Henry and Zhou Mi are members of the sub-group Super Junior M which performs songs in Mandarin Chinese.
Currently though, there are only 10 members active right now. Kangin was arrested for getting involved in a fight outside a bar with 2 other people and later got into a car accident because he was intoxicated at the time. He has enlisted into the army and has not participated in the 4th album. Kibum decided to pursue his acting and Hankyung filed a lawsuit against SM because of unfair treatment and restrictions in his contract. They are all not involved in Super Junior's activities.
Since Hankyung was the leader of the sub-group Super Junior M, Henry and Zhou Mi are now left hanging because the group is not active.
Super Junior H (Happy) recently released their World Cup song called Victory Korea =)
So a quick run-through of all sub-groups (4 total)
Super Junior M~ Hankyung (leader), Ryeowook, Siwon, Donghae, Kyuhyun, Henry, Zhou Mi
Super Junior Happy ~ Leeteuk, Yesung, Sungmin, Eunhyuk, Shindong, Kangin**
Super Junior K.R.Y. ~ Yesung, Kyuhyun, Ryeowook
Super Junior T (Trot--an older form of popular Korean music) ~ Leeteuk, Heechul, Sungmin, Shindong, Eunhyuk, Kangin**
Kibum is the only member who is not in any sub-group
There are fans who believe in SuJu as 13, excluding Zhou Mi and Henry, others believe it should be "13 as a group, 15 as a family" it really depends. But with 3 inactive members some added Zhou Mi and Henry...yeah I know it can be a bit confusing ^^
But don't stop supporting Super Junior, I can't believe there are people giving up on groups that have members leaving.. I don't know where are all these fans are going, people were bashing 2PM when Jaebeom left, then there was the DBSK lawsuit controversy/indefinite hiatus and everyone freaked out.. They need us as supportive fans!
I hope that makes it less confusing.. =)
@Allie_13 ~I don't think it was necessary to mention that SuJu is "better" than SS501 =(
They make completely different kinds of music and each group is unique. It depends on everyone's taste in music. I really like both of them in their own way ^^