に限(かぎ)らずNot just, Not only… but also

だけでなく and に限らず both express non-exclusivity, but differ in nuance and formality. だけでなく is a straightforward expression meaning 'not only (A), but also (B)', and is often used in everyday conversation (especially in the variant form だけじゃなくて). In contrast, に限らず has a more formal and academic tone, and carries a slightly different nuance, suggesting that whatever follows is 'not limited to' the thing in question.

はもちろん emphasizes something obvious before adding another case, e.g. 日本人はもちろん留学生も来た ('Not only Japanese people but also exchange students came'). に限らず expands the scope of a statement, implying 'not limited to (A), also (B)', e.g. 子供に限らず大人も楽しめる ('Not only children, but also adults can enjoy it').

Both are fairly formal patterns which convey that something applies to more than one item, but they differ in nuance. ばかりでなく is a relatively straightforward 'Not only (A), but also (B)', e.g. 日本語ばかりでなく、韓国語も話せる 'He can speak not only Japanese, but also Korean.' In contrast, に限らず has a more specific nuance of 'Not limited to (A)', e.g. 学生に限らず誰でも入場できます 'Not limited to students, anyone can enter.'

をはじめ highlights one example among similar ones, e.g. 日本をはじめ多くの国で使われている ('It's used in many countries, starting with Japan'). に限らず expands the scope beyond the first item, e.g. 学生に限らず誰でも参加できる ('Not limited to students, anyone can participate').