An aerogel fabricated by forming an aqueous suspension including carbon nanotubes and a surfactant, agitating the aqueous suspension, and centrifuging the agitated suspension to form a supernatant including the carbon nanotubes. The supernatant is concentrated to form a concentrated suspension including the carbon nanotubes, and a hydrogel is formed from the concentrated suspension. The hydrogen is contacted with a strong acid to form an acidic hydrogel and to remove surfactant from the hydrogel, and then neutralized. An aerogel is formed from the hydrogel. The aerogel may consist essentially of carbon nanotubes. A composite may be formed from the hydrogel or the aerogel by infiltrating the hydrogel or the aerogel with a polymeric material and curing or pyrolyzing the polymeric material. The composite may be electrically conductive, transparent, flexible, superelastic, or any combination thereof. A device, such as a flexible conductor, sensor, or electrode may include the aerogel or the composite.