| St Helens trolleybus system | |
| Locale: | St Helens, Merseyside, England |
| Status: | Closed |
| Routes: | 6 |
| Operator: | St Helens Corporation Transport |
| Stock: | 66 (maximum) |
The St Helens trolleybus system once served St Helens, Merseyside, north west England. Opened on, it gradually replaced the St Helens tramway network.
By the standards of the various now-defunct trolleybus systems in the United Kingdom, the St Helens system was a medium-sized one, with a total of six routes, and a maximum fleet of 66 trolleybuses. It was closed relatively early, on . The 16 youngest trolleybuses in the fleet at that time, ones built in 1950–51, were all sold to other systems for further use. Eight Sunbeam vehicles went to South Shields system and eight British United Traction vehicles to Bradford.
Only one of the former St Helens system trolleybuses is now preserved, at the Trolleybus Museum at Sandtoft, South Yorkshire.