SPICE Model Links
Begin by Googling 'part name' "SPICE model", usually it's enough.
Christophe Basso LTspice PWM models and lots more
Large list from elektronikschule.de
Another nice list of links from Penzar Development
Links to many companies' SPICE models from emwonder.com
Opamp, Voltage Comparator, Voltage Regulator, Voltage Reference Models Use caution, may be a copyright violation.
Modifying an existing SPICE model
Littelfuse Thyristor SPICE Models
Vishay NMOS Note: hover over the 'i' icon, and you can select the SPICE Model.
Würth Elektronik LTspice models