Is there a right to self representation in civil cases in Illinois?

Any competent individual has a right to represent themselves in court.  For Federal Courts, this right is codified in 28 U.S.C. Section 1654.  I do not know if the rule has been codified in any Illinois state statute or rule, or is merely part of the common law, but I am confident that the right exists in Illinois state courts as well.  With very rare exceptions, however, a non-lawyer cannot represent anyone else, including any corporation, llc, or other entity.