Recall the classification of proteins

Proteins are broadly classified into:

• Fibrous proteins: long, thread-like, generally insoluble in water, mainly structural in function.
• Globular proteins: spherical, generally soluble in water, often functional proteins such as enzymes and transport proteins.

Check each option

A: Keratin

• Keratin is a fibrous protein.
• It is found in hair, nails, wool, etc.
• So, A is an example of fibrous protein.

B: Albumin

• Albumin is a globular protein.
• It is water-soluble and found in blood plasma and egg white.
• So, B is not a fibrous protein.

C: Collagen

• Collagen is a fibrous protein.
• It is an important structural protein in connective tissues.
• So, C is an example of fibrous protein.

D: Myosin

• Myosin is generally treated as a fibrous protein in standard biomolecule classification.
• It is associated with muscle contraction.
• So, D is an example of fibrous protein.

Conclusion

The option which is not an example of fibrous protein is: $\boxed{\text{B: Albumin}}$