Linked from
The 21 pages that link to W and Z bosons, each with the reason it gives.
Higgs mechanismBroader topic: Their masses arise from the Higgs mechanism in electroweak theory.
BosonBroader topic: Their spin-one nature makes them bosons that carry a fundamental force.
Gauge bosonBroader topic: Their large masses make the weak interaction short-ranged.
Electroweak symmetry breakingBroader topic: They acquire mass from the Higgs field’s vacuum value.
Robert BroutBroader topic: Their masses are explained by the mechanism Brout and Englert proposed.
Force carrierBroader topic: Their large masses help make weak processes short-ranged.