The organelle other than the nucleus containing DNA is mitochondria.
Explanation: While the nucleus is the primary organelle containing DNA, mitochondria also have their own small amount of DNA called mitochondrial DNA (mtDNA).
Why other options are incorrect:
Endoplasmic reticulum:
The endoplasmic reticulum is involved in protein synthesis and lipid production but does not contain DNA.
Golgi apparatus:
The Golgi apparatus modifies and packages proteins but does not contain DNA.
Lysosome:
Lysosomes are responsible for breaking down waste materials and do not contain DNA.